Instead of using TF&SC (currently for TB 60 and lower), try this: Preferences(Windows:Tools/Options)/Advanced/General/Config. editor, right-click the preference layout.css.devPixelsPerPx, Modify, and enter a value of 1.20 or 1.25 or 2.0. The change takes effect immediately without closing Config. editor, but make gradual changes to avoid making the display unreadable.

See the pictures here and other comments in that thread.

If you want a more precise method for the fonts, see this post:

https://support.mozilla.org/en-US/questions/1269361?page=2#answer-1274848

I should have said that I use Thunderbird on my Mac. Can you give me instructions for mac

The instructions above for changing the preference are for Mac: Preferences/Advanced/General/Config. editor. You can also click the 3-bar AppMenu, then Options/Options.

If you use the css method, open the profile folder from Help/Troubleshooting, click Show in Finder, then close TB before making any changes.

Seriously??? There are several "pages" to scroll down and I don't have any idea what they mean. I'm not interested in writing code to get a larger font.

Can you please tell me where I can go to download an earlier version of Thunderbird that works with legacy extensions.

Hi Judi You don't need to read through all those lines - just type into the search box - layout.css.dev That will show you only the one setting you need. Changing it is easy - right click, choose Modify - type 2.0, click OK. Be brave! It's not really writing code, just changing a single setting. Way easier than trying to revert Thunderbird to an earlier version. Best wishes, Agnes

This isn't what my Preferences box shows. There is no Advanced icon so I went straight to General, but there is no advanced option on that screen. Can you please tell me what I'm missing?

sfhowes said

The instructions above for changing the preference are for Mac: Preferences/Advanced/General/Config. editor. You can also click the 3-bar AppMenu, then Options/Options. If you use the css method, open the profile folder from Help/Troubleshooting, click Show in Finder, then close TB before making any changes.

Abrasrose said

This isn't what my Preferences box shows. There is no Advanced icon so I went straight to General, but there is no advanced option on that screen. Can you please tell me what I'm missing?

It appears you are looking at Firefox Options, not TB.

https://support.mozilla.org/en-US/kb/config-editor#thunderbird:mac:tb68

Hi Abrasrose - The original poster was using Mac OS 10.14., and the answers were specific to that OS. If you are not using MacOS, those instructions may not work for you. Agnes

I followed the instructions above and the font size didn't change. I probably haven't been clear. I'm talking about the column that lists the email. Should that have changed?

Hi This post, as mentioned earlier, has pictures which show exactly what increases when changing this setting. https://support.mozilla.org/en-US/questions/1269361#answer-1254162 Agnes