Change Default Typeface in FrameMaker?

Are you referring to the actual program's typeface and font size OR documents created? And what version of FM are you using in what environment? (Always good to mention that in any post)
Sometimes the settings need to be tweaked to display properly on high-resolution monitors.

Hi,

Generally you can change the font of all paragraphs formats in a document.

Open the Paragraph Designer and go to the Font tab. Change the font and click Update Style to change the default font of the format of the current paragraph.

When you want to change the default font of all paragraph formats, click outside of the main text frame. (Then all settings in the Paragraph Designer are set to As Is.) Then open the Paragraph Designer and go to the Font tab. Change the font and then click the gear symbol in the bottom left of the Paragraph Designer. Select Global Update Options and then Default Font Properties Only and All Paragraphs and Catalogue Entries and then Update.

When you want to change several paragraph formats, select all of them and then in the Global Update Options select All Matching Tags in Selection.

I would not use a template file in the FrameMaker template folder. Then it will also use the path to any images on the reference pages or template pages. Other images which you insert might be in another folder. This mixture can create problems.

Best regards, Winfried

If you are creating new files from organizational templates, they would need to be revised.

If you are using FM's
File🞃New>

feature to start a new file or project, they are just templates, usually found at and below:
C:\Program Files\Adobe\Adobe FrameMaker 20##\Templates\…
You might need Admin privileges to modify them, and there are rather a lot of them, probably most of which you never need.