I hadn't given any thought to how the forum looked on my cell phone Vs my PC. I wouldn't even know how to install fonts onto the phone, I guess that's why the creators of this forum chose the font they did.
(Personally I always preferred Times New Roman over Ariel, but find Courier New to be better for displaying numerals in work documents as it keeps the values in readable columns).
Don't fall into font modifications is the best, in my opinion. The default font (on computers or mobile - phones, tablets) is san-serif, so it works well originally. There is no need to modify it and makes it harder, uncomfortable for readers.