To be able to make changes to the Identity module a box in the Maintenance settings has to be checked. This can be done by clicking on ‘Maintenance’ and unfold the ‘Settings’ menu on the right. The box ‘Has own guidelines’ needs to be checked.
It is possible to upload a new font in Brandifyer. However this will not change the font in Brandifyer, it is purely meant to show the fonts and to make them available for download. In Brandifyer go to the ‘Identity’ first and click on the ‘Typography’ category. On the right click on ‘Edit this page’.
This article also has a Youtube video to show how this action can be done.