During the full install, use the Manual Option.

If you want to leave feedback for Firefox developers, you can go to the Firefox Help menu and select Submit Feedback... or use this link. Your feedback gets collected by a team of people who read it and gather data about the most common issues.

Use the full installer from here: https://www.mozilla.org/en-US/firefox/all/

Most links to download Firefox are for the stub installer which doesn't offer the Custom installation option.

That said, a Custom installation can be used to install Firefox on the D:\ drive, but the bulk of Firefox files (the Profile folder with your Firefox data files and the Cache) will end up on the C:\ drive (or where the operating system resides) in the User \ AppData grouping of files.

There is nothing in the Custom installation routine, now or ever, which allows the user to select where the Profile & Cache reside.

Bottom line: My advice is to use Firefox Portable,from Portable Apps and install it on your D:\ drive. It is a 3rd party application (not from Mozilla directly) which has been around almost as long as Firefox. https://portableapps.com/support/firefox_portable

It will keep all its files on the drive where you install it. IOW, totally self contained. But it doesn't write to the Windows Registry, so Firefox Portable can't be made the "Default Browser" in Windows and there are a few other shortcomings in that vein.

I always have Portable Firefox version installed and hidden from view, for "activities" that I wouldn't want children to see. IOW, no icon visible anywhere, it launches only via keyboard commands.

savara said

I know this is a users helping other users forum, but maybe someone can help me figure out how to contact the people that can actually do something with negative feedback. I cannot find an email to Mozilla to send a complaint. I cannot find any way of contacting the company. Firefox used to have custom installation built into their installation download, making it super easy to set it up on the D drive.

Mozilla does not have the resources to have call centres for one on one support by phone, chat, or email, especially since it would be for free. Any products that do have such one on one support are usually paid for products.

Mozilla has served the stub installer (for Windows users) on www.mozilla.org since it started existing as of Firefox 18.0 as the full offline setup for Windows can be downloaded from www.mozilla.org/firefox/all/

Besides here there is the Mozilla newsgroups and irc.mozilla.org.