Hi,
I'm having the same problem. I also have an "old account." I can was able to change my frontierstore.net password, but not my forum password, which Safari tells me was compromised in a data breach. I can also login with the leaked password, and only the leaked password. It's funny, often times sites don't even have an account section that says "password," and you have to dig a bit to find it. The Frontier Forums site DOES specifically have a "password" section, but there's absolutely no way for us to change our password. Pretty dumb TBH.