The fonts within a document can be sourced from a couple of locations - centrally from a font package, or from the document's own 'Document Fonts' folder.

Click the drop-down menu and choose an option for the document fonts.

The default is to allow each document to be tailored in the 'Project Details' window (as shown below). Other options are to force documents to always use the centralized font packages on the workspace. Alternatively, you can force documents to always use the fonts from their individual 'Document Fonts' folder.

Here is a screenshot of the 'Project Details' window, showing the options that can be chosen if the 'custom document settings' are allowed for fonts.

We can see that the options are:

1. Use all centralized font packages from this workspace
2. Choose a specific font packages from the centralized packages
3. Choose a specific font folder for this document