To change the font attributes in GnuCash you need to create or edit a gtk-3.0.css file.

$ vim  ~/Library/Application Support/Gnucash/gtk-3.0.css 

gtk-3.0.css

* { 
  font: 14px arial, sans-serif; 
}

sudo /Applications/Gnucash.app/Contents/Resources/bin/gnc-fq-update

I recently had the above command fail and it ended up being that “Test2” had to be update before “DateTime::Format::Strptime”, or it's dependencies, would install.

$ sudo perl -MCPAN -e shell
> upgrade Test2
> upgrade DateTime::Locale

Another way that I was able to get Finance Quote installed on Big Sur 11.4. I was having issues with getting Finance Quote 1.51 to install.

sudo cpan install App::cpanminus
sudo cpanm Finance::Quote@1.49