Greetings!
I’m trying to install a font to make it my default terminal font. I tried double clicking the downloaded file, which opens the font app, and then clicking the install button. Then I go to the terminal app, select preferences, then check the box for using a custom font to select the font.
This is where things get funky.
At first, the sample text shows a different font (Cousine as it seems), not the one I actually selected. The app doesn’t prevent me from clicking ok which I proceed to do. To no avail. Terminal now shows a completely different font.
If I try the Zorin Appearance app, I can select a default monospaced font. Now something odd happens. I select the desired font, confirm and re-open the Appearance app. Now it falls back to Cousine.
Apparently the font is correctly installed. Maybe it’s some permission issue, but I find it funny that no error message whatsoever is displayed.
Thanks in advance.
Best,
Luiz
Is the font installed in your home folder or in root?
~/.fonts
/usr/share/fonts
Did you logout/reboot after installing the font? 
Hmmm - just installed Comic Sans and it is not showing. I think this is a 'root' permissions issue. The way to do it correctly is via a terminal.
Open Terminal (Ctrl+ Alt+ T or Menu | Utilities | Terminal) and
cd ..
cd ..
cd usr
cd share
sudo chown [username] fonts (if TrueType font you might want to cd .. further ...
cd fonts
then
sudo chown [username] truetype
You will be asked for your login password - this means the protected system folder of fonts is now read/writable. Now open your chosen file explorer, go to Computer or File System, navigate to usr | share | fonts | [truetype?] and drag your downloaded font into the folder.
Then reboot and you should have your new font.
This is where KDE excels over Gnome as it has a Font Manager where you just add fonts to either 'Personal' or 'System'(-wide) fonts - so much easier.