Don't know why but changing the fonts or size has no effect at the moment.
Somethin is overriding this i think but i don't find it.
Could you take a look?
Thank you so much!
Please, turn off all plugins, refresh your cache, and check if the problem persists.
Moreover, if you use a child theme, switch to parent, and recheck it.
If this will not help, please, tell me which fonts you changed and what size they should be.