I cannot undo an extreme zoom in Theme Font and Size Manager-Tbird now unusable. Restarting w addons disabled & reinstalling Tbird didn't work.
I can no longer access the Theme Font and Size Manager to reset the zoom---it is too large, and the controls can't be seen. I can't read messages, either, or move around in a message.
Additional System Details
- User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0
Try this: In Thunderbird Help > Troubleshooting Information click on 'Open Folder'
a window opens showing contents of 'profile name' folder
Exit Thunderbird now.
Locate and delete the following files
Start Thunderbird in Safe Mode - see info at link below:
Does everything start ok in Safe Mode ?
Restart Thunderbird as normal. Does everything look ok?
It sounds like this would help if I could access the folders, but I can't. I can get to Troubleshooting Info, but I can't find an option called "Open Folder." Since it is still zoomed 400%, it's hard to see what's there for sure, but I did scroll down to look for "Open Folder" under both the File and View menus under Troubleshooting Info.
Modified by L8Bloomr
I solved the problem! I did what should have been obvious from the beginning---used my laptop's touchpad zoom feature to counteract the zoom in Thunderbird so I could see Theme Font & Size Changer more or less normally and adjust the settings.