After impose template, font change still affects many elements
I wanted to change the font in only one element among many that use a certain template. As per your documentation, I choose Impose template and answered Yes to Detach template?. However, when I later changed the font by Edit font, all the elements that used the imposed template changed that font.
When you choose Edit font you edit that particular font. It will change in all elements and templates that use that font. Instead, you should use New font to create a new font with new properties. Still, you must impose and detach the template to make sure the new font is not linked with all elements that use that template.