You might want to look at Firefox help here. It has to be done from the older computer to move to new computer.

https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Hi, markwarner22

     Thank you for your reply, appreciated very much. I will try and see if your help and instructions will do the trick. Please give me a little time get things together with my other computer to try and see if the bookmark transfer will work. I will get back to you with the results. Again, thank you markwarner22 for your help.

Make sure to us a USB drive so that the iOS will be able to read and import the data over.

Hi markwarner22,

   Thanks again for your reply. Your comment, "Make sure to us a USB drive so that the iOS will be able to read and import the data over." may be the reason I'm having trouble transferring my Firefox bookmarks to my iMac computer? I followed your instructions as per the transferring book marks and I'm pretty sure it was done correctly. But, I'm having difficulty in being able to transfer those bookmarks to my Apple computer? I see with the iMac OS it has a provision? to make that bookmark transfer. But, I just can't see those exported bookmarks with the Apple computer? Part of my problem may be I'm just not a computer wizard and I'm missing something I should be doing that maybe most might find elementary? Can you help and explaining use a USB port drive as you mention? Does that mean connecting a USB connector between both computers? I have never done what I'm trying to do, so I would appreciate your help and patience. Hopefully you can help my situation as I would like to use the later model computer I have acquired. Certainly appreciate your help and patience with a novice computer user. Thank you, markwarner22.

Hi Markwarner22,

   Let me explain what I have done so far. I sure I executed the export bookmarks from the https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer. I put the exported bookmarks to desktop like you suggested. The issue seems to be when I go to my iMac from the HP computer where the bookmarks were exported.  When I open Firefox in the iMac I go to bookmarks then manage bookmarks. I then go to import bookmarks from HTML. I then get a window, at the top of that window I see a library link, but there are other options also, like desktop and another half dozen options.  But, I then hit a stone wall after I click on either library or desktop. There's a link at the bottom that says cancel or open. I certainly would think I would want to open the open link, but that olption is not open, only cancel? Can you possibly explain what is happening and why I can't open either library or desktop? 
   I would appreciate your help, markwarner22. Can you help and explain why I can't seem to import my bookmarks from my HP computer to my Apple? Thank you, markwarner22.

Did you use a USB drive to store the data? And was the Mac able to see that data as well?

markwarner22,

     Thank you for your reply. I did install a USB flash drive when I executed the export bookmarks procedure. Little surprised if all those bookmarks were downloaded to that USB flash drive? But, what do I do now with that USB flash drive? Do I plug it into the UBS port on the iMac computer? Is that how the Apple computer "sees" those exported bookmarks, markwarner22? Appreciate your help. Thank you, markwarner22.

Can you edit your replies so they aren't scrolling text?

markwarner22,

  Sorry how the replies are being sent. I can see how that would be annoying!!! But, when I tried to remedy the problem, it seems I get a dozen fixes? Can you give me a simple one fix solution to change my replies from a scrolling text and are normal. Frankly, the way they used to be sent. Don't know how or when the change happened? Still would like to solve my bookmark issue once we solve this text issue. Thanks again, markwarner22.

markwarner22,

  Can you please explain how I can avoid the message reply problem? Can't seem to find a Firefox solution? 
   On another subject I was able to put my bookmarks on a USB drive. When I viewed the contents of the USB drive it did show my bookmarks. So the USB drive has them. How do I now import them to my iMac, markwarner22. Can you please help. When I plug in the USB drive I don't see a option to import them. Thank you.

You are using leading spaces in your replies and that makes the forum software render them in PRE tags. Can you open the HTML file is a Firefox tab?

• https://support.mozilla.org/en-US/kb/import-bookmarks-html-file

Hi cor-el thank you for your reply. I am able to execute import bookmarks from HTML. The problem is when I try and go farther. I'm transferring the bookmarks from a HP computer to a Apple iMac computer. And maybe that is the issue? But, when the next window opens on my Apple computer after the import bookmarks HTML execution it shows a window that has options at the top. Those options are untitled folder, desktop, rickherrick,users,ITB HDD and Rick's Mac. When I click on the desktop option, which is where it was recommended to put those bookmarks, I can't click on the open option as you state. Eve when try any and all of those options I can't open the folder/file that evidently has my bookmarks. I have tired numerous time to execute that last procedure. But no matter how I try I can't open the bookmark HTML file/folder. I tried to to a screen shot of the Apple iMac box window that appears when I execute import HTML bookmarks, and then click open procedure, but evidently the Apple system won't allow a screen shot when that window is open??? So, I'm just frustrated I can't do this transfer of my bookmarks from my old HP to my Apple iMac. To make matters worse, my replies seem to have a text peculiar format that I can't remedy? So, hoping you cor-el might have some input as to how I can make a bookmark transfer to my Apple computer. I did by the way was able to download my bookmarks to a USB flash drive on my HP computer, but now the Apple computer can't seem to open the USB flash drive that has those bookmarks? Just one problem after the next. Sure hope you can be of help, cor-el. You certainly have in the past. Appreciate any help you can be.

Hi cor-el, I was able to transfer my bookmarks to my iMac computer. I used a USB flash drive. And was able to finally complete the task. But, now I have the problem of way to many bookmarks are in the bookmark line up. Is there a special way delete a lot of bookmarks with in that bookmark listing? Is there a way to possible drag the cursor through a lot of bookmarks and delete them that way?

Can you open the file via "File -> Open File" (Command+O) or drag the file in a Firefox window?

This might be a permission/sandbox issue where Firefox doesn't allow you to access the desktop, so maybe save the file to a folder in your user directory.

Hello cor-el, thank you once again for your reply. I just simple went ahead and deleted the extra bookmarks manually. Took a fair time but it happened. I have another question pertaining to the menu bar on Firefox. The text is rather small on my iMac computer. Can I make that menu bar larger, height wise so the text isn't so small? Can I do something like that with Firefox? Or, is that a Apple issue? As always appreciate your help, cor-el. Thank you.