I was using a free account and the font size on the Dashboard and menus was much easier to manipulate than the huge font on my school account. Is there a way to change that setting?
It's a little tricky to be able to support you without know some extra detail.
Has your institution got an extra tool built into Canvas that has made the Dashboard experience different to your Free For Teacher?
I'm wondering if the new Rich Content Editor experience is proving challenging for you also. Here's a link for guides for that. This won't impact the Dashboard, but will possibly make a difference to your editing possibilities within courses.
Sing out if you need a hand.
Post us a screenshot - and we might be able to help more. Is it just your screen, or does everyone in your school have huge font? If it's everyone, then my best guess would be that your administrator/webperson has overridden the font size in Canvas in their HTML whitelist, and needs to remove/edit it. Canvas tweaks the HTML all the time, so generally people suggest not playing with the font sizes too much.