Accessing my riseup account

My spouse has been sick for over a year, and for the last six months hospitalized, during which time I did not use my riseup email account. Within the last few days I've again tried to begin using it, but found I apparently didn't remember, or got confused as to my password. I've had several over the last couple of years. I've tried fixing the situation by changing the password, whereupon I still cannot --using the new password-- access the account. I simply get 'login failed' over and over again. I'm obviously missing something. I tried changing my username, and attaching a new password to the new username. Still can't get it to work. I've read over information on the site that seemed relevant to fixing the problem. I have a sneaking suspicion that there is something I've forgotten, that were I to remember it, I've be about to solve this. But, so far I can't put my finger on it. Can anyone offer me some possibilities that might move me in the direction of solving my problem?

I should mention that up until now I've used an alternate email address that I would rather stop using and replace with one I have more confidence is private. I do have one I'm more confident in, but I'm not sure how to replace the old alternate with it.