How to change the font size? atop xterm, aterm, etc

[jb_daefo]

For instance, I have 10 tabs open in a
browser, to "new posts". As I read each
one, in *tiny print* in the titlebar (to
the right of which includes the minimize, , close
buttons)... is the thread title.
Where can that font/and.or/size be increased?
in .Xdefaults? in the settings for the theme
in the window manager? in xinitrc ???
...........
Knowing that would speed up browsing by five
or ten percent, I conjecture...