Fonts not responsive

if it is you page ( and your nick is very informative ) i think you have uploaded only that montserrat font (and gotham-pro) via the fontmanager – but you have uploaded the whole downloaded font zip file.
Inside that zip there are variable font files and in a subfolder the static font files.
your static font folder leads to the result that the Montserrat Font is listed as font-family: static

By the way :
new Enfold can also handle these variable font files – but I would recommend uploading them separately.

For example, put the Montserrat variable files in a folder and name it Montserrat-variable.
Pull out the static folder from the zip file and rename it to Montserrat.

For performance reasons, it is now time to consider whether you really need all the fonts. The list is very long, especially for Montserrat. In principle, the variable fonts should be sufficient for all modern browsers.

However, if you only need, for example, light, regualar and bold, it may even be better to upload only the static fonts (woff2, ttf). In addition, Montserrat is a font where the italic variant hardly differs from a normal slanted font.
You could therefore live with the fact that only the normal font styles are uploaded and the italic fonts are converted by browser rendering.

Then zip these two folders (please not in Mac Zip format – so without all the invisible files OSX packs in), but without the metadata. Betterzip also has a “zip for PC” option.
Then upload these folders to the font manager.

PS: the uploaded Fonts can be found at the bottom of the font dropdown list ;)

if you set up a rule on “Advanced Styling” for example for a h1 – the rule is noted as:

#top #wrap_all .all_colors h1 {
  font-family: 'brush script mt',Helvetica,Arial,sans-serif;
}

the selector got 2 IDs – so it has a high specifity (https://www.w3schools.com/css/css_specificity.asp)
and see how the specifity counts: https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity

But if there is another rule f.e. in quick css that got a higher specifity – or is set to !important – “Advanced styling rule” is ignored.
f.e. as: #top #wrap_all #main .all_colors h1
For this reason, I add rules to my Quick CSS with at least one ID (#top) that should “win”.
I try to avoid using !important.