What version of PHP are you running? Are you running your server over a CDN? What web server?
What happens when you put names BACK in the box and submit? How are you changing the names? From the "Edit Forum" script or from the "Forum List" page?
I added UBB to my bluehost account and that seemed to fix the problem. I was just using namecheap because my domian is there and i don't have to transfer it over.
It sounds like it's an issue with some non-standard configurations at namecheap; discount hosts can run into all sorts of weird configurations due to the mass packing of users on their services. BlueHost is a great option.
As for changing design elements, such as fonts, see the Style Editor and edit the default style. Be careful with adjusting padding, margins, and introducing additional HTML as it can break the mobile capability of the forums.