Can't access shared Box account

Hi. A company shared a Box folder with me several years ago so I could share docs with them. That email address is now defunct. That same company is now sharing another Box folder with me at my new email address, but Box defaults to my old defunct email address in the browser. It doesn’t give me the option of entering my new email address. However, it asks me to reset my password, and it will send the reset link to my new email address. I have gone thru the steps and successfully set a new password. However, when I try to log into Box with the new email address, it says the password is expired and my only option is to reset the password. So I’m stuck on this endless loop. Any ideas how to fix? Thanks.