Menu app icon > Font Size click on the + to increase font size - repeat until size is ok

Or via Menu Bar toolbar View > Font Size > click on 'increase font size' - repeat to get desired font size.

The View > Font Size function no longer works on my Windows 11 desktop. The problem began only yesterday (11/24) I have now updated to Thunderbird 115.50. That didn't help.

I can barely make out the menu items or lists. Any help will be appreciated.

I accidentally reposted my reply. I don't see a way to delete it.

The View > Font Size function no longer works on my Windows 11 desktop. The problem began only yesterday (11/24) I have now updated to Thunderbird 115.50. That didn't help. I can barely make out the menu items or lists. Any help will be appreciated.

Need some info: What 'Density' setting is selected?

• View > Density > ?

What px size is shown in this location?

• Menu icon (3 lines) > Font Size > ?px

Check the following is set to default:

• Settings > General
• Scroll to bottom and click on 'Config Editor' button
• In search type: pixels
• look for: layout.css.devPixelsPerPx

By default it should be a negative number -1.0 If you see any other number then do this:

• click on the pencil icon on the right
• Completely remove whatever number is in that area
• type the negative number: -1.0
• click on the tick icon to save.

Confirm you have the default -1.0 setting.

Whilst in this area check this:

• In search type : uifont
• look for : mail.uifontsize

By default it should say zero 0 which means the default of 12px is being used. What do you see ?

Thank you. I had done those things without success, however, last night I tried once more to increase the font size in Windows settings. This time it worked. When I went back to Thunderbird. the option in View>Font Size worked again and I was able to increase and decrease the font size again.

Unfortunately, now other parts of the Windows GUI are too large. For example, the three toolbars (open tabs, main toolbar, and bookmark bar) in the Opera browser take up about 20% of the screen, but that's a problem for another day. Thanks again.

You have had issues with font size and I'm aware that you have posted your frustrations about this issue in other forums without success. Using 'Windows to mess about with font size will effect everything on your computer, so it is not a solution.

In order to get a real solution you need to work with me because I have sorted out several cases were things were very much out of synch. That means you need to post requested information and it would be helpful if you did not alter things otherwise I'm offering instructions which may not work.

So far, I've asked you to set up a certain settings so I know we are working from a good starting point, but that's all - I've not offered you any solution.

Please tell me the answers to questions.

But first put your Windows settings back to where they should be.

In Thunderbird. What 'Density' setting is selected?

• View > Density > ?

What px size is shown in this location?

• Menu icon (3 lines) > Font Size > ?px

There are various areas that need to be checked when it comes to font size settings in Thunderbird.

Confirm this setting : layout.css.devPixelsPerPx is set to the default negative -1.0 What is the number you see for this: mail.uifontsize

Need to understand all other font settings.

• Help > Troubleshooting Information
• scroll down to 'Important Modified Preferences'
• Look for where it starts with : font
• Copy ALL in the list for items that start with 'font'
• Paste the information into this forum question.

Tools > Addons & Themes OR 'Menu app icon > Addons & Themes What theme you are using in Thunderbird?