Some products i sell only uses 1 font. When i select that font in indiv. product settings, the text on the FPD is still in the site's default font instead of the one font i chose.
How can i change it so it uses the right font?
Mayby somebody from support?
Sorry, in that case opening a support ticket is the quicker way. You have tried simply removing the default font setting in the main settings, default element options, default font?
Is it possible assign a font group for each products? I'd like to have the product A with 3 fonts and the product B with other 2 different fonts.
Yes you can do that in the individual settings, on the WooCommerce page, general tab, available fonts:
In the future please create a new thread for a new question.