Assign Font to default Blocks

Hi.

I use your theme and Blocks Plugin.

I Uploaded fonts for the preset fonts in your theme options to host locally and have presets. Works fine.

Question:

I have a default gutenberg block. How can i assign to this block the uploaded fonts? I only can see the default Gutenberg fonts.
It is necessary because the header navigation is not a gutenshift block and the menu has now another font.