You would change the font in the menu by using custom CSS like this:
.menu-block .gf-menu .item {
font-family: arial,sans-serif;
}
This is how to create a custom CSS compatible with Gantry 4...
Simply create a file called "<TEMPLATENAME>-custom.css" and put this file in the CSS folder of the template (where <TEMPLATENAME> is the name of the template as seen in template manager e.g. rt_iridescent would be rt_iridescent-custom.css). GANTRY4 will automatically load this CSS file. If you wish, you can also have browser specific files by appending, for example, "-ie9" making the filename "<TEMPLATENAME>-custom-ie9.css"
If you want to use your own font, please see this page for a tutorial on adding fonts to one of our templates
http://docs.gantry.org/gantry4/tutorials/adding-a-custom-font
.
If you need more help, Please would you post your URL, superuser id and pswd in the secure tab of your post and i'll have a look for you.
Regards, Mark.