Hi,
This is one of the rare occasions that you would go into the XML Source tab. However be warned you can break your form, so I would recommend doing this on a copy.
Drag in a new object and set its font to the one you want. In the XML Source tab you should check the string that specified the font.

Select an object and click on the XML Source tab. Scroll down to where the font is specified and select the font name. Under Edit menu do a Find/Replace with the new font name.
Go back to Design view (click OK) and then test.
Hope that helps,
Niall
Assure Dynamics