Thunderbird font

What is the correct way to change the source of thunderbird?

I can’t change it through the menu Preferences -> Display -> Formating.

I’ve already changed to giant numbers like 72, or much smaller and nothing changes in the interface. Not even when rebooting. Changing the default font doesn’t make any changes either.

I have a small monitor and the letters are too big. The icons and buttons are also out of proportion.

The only extension available for this is no longer compatible with the latest version.

I like to use thunderbird, but for a software with such a long existence and mozilla brand, it is still very limited.