Change is sometimes difficult to adjust to, but for what its worth, I use this same software on a automobile-related forum I've been running for 20 years. At first, my members balked at the change, but once they got used to it, they really love it. Xenforo is a relatively new forum software, but it's capabilities, in my opinion, are phenomenal. As for the font size - the admin could install additional "Styles" with bigger fonts that the users could choose. In the mean time, on most browsers you can manually make fonts bigger, usually very easily. Not sure what browser or operating system you use, but I use Safari on an iMac and each time I press Command-"+" the fond gets larger. If I have trouble reading something because it's too small, I press that key combo a few times and viola! You might try that.Maybe I missed it, but I didn't see a warning the site was going to be "updated" and am trying to get use to it. I find myself logging in less and have lost the desire to respond to posts. One of my issues is the smaller fonts used in some situations, which are very hard on older eyes. Has "active topics" been replaced by "what's new"? In any case, I don't see the changes as positive.
I reported it a week ago. Apparently the Techs are aware so presumably something will get done at some point.