Beginner needs HELP, please!

Greeting,

I have spent close to two hours attempting to find out how to increase the font size on my email (I use Mozilla Thunderbird) and the tool bars when I use FireFox (though I can use command + in Google and Gmail) but I cannot use this function in Thunderbird. When I go to the view to zoom in or out, the chose is grayed out. I tried what was suggested at Mozilla but my problem has not resolved.

If I open Firefox, the top task bar is tiny (same thing with Thunderbird) and am trying to make it larger.

Any suggestions would be appreciated. I just installed Marvick and this issue started as before, I could make the adjustment with my command + or - keys.

Thank you so much!

For Thunderbird go to Tools -> Options -> Display -> Formatting -> Fonts...

And this for FF:-

https://addons.mozilla.org/en-US/firefox/addon/make-address-bar-font-size-big/

Trying add a theme to FF and Thunderbird - that will give you more options. I use Silvermel, and right in the toolbar there's an option to increase font size.