The reason is that you used to used an old password (we can see from your account that you’ve used AxCrypt for almost 2 year).
You did not *change* your password yesterday, you *reset* it.
If you do not remember the password to your account, you can always reset it. This is not a way to recover encrypted files! It’s only to allow you to sign in to the AxCrypt app and web. The new password will be used to encrypt new files.
If you open files encrypted with a different password than your sign in password you will be prompted for that original password.
Unfortunately, if you do not know the password for an AxCrypt-encrypted file you cannot open it, even if you can sign in to the account. This is by design, it’s just this situation that AxCrypt is made for and it works like this even if you actually are the original owner of the file.
You need to remember the password you originally used to encrypt the files!