To change a RIPE maintainer password you first need to generate a hashed version of it here:
Then navigate to the Webupdates interface to edit your maintainer object:
Enter your current password in the left sidebar (and click “Add”), enter your maintainer name into the “Search” field and click “Search” - You will be redirected to the edit interface.
Enter your new auth string in the “auth” field and click “Update”.
Your maintainer password is now changed.
Tip: Multiple maintainers can be added to the same object, avoiding the issue of having one password for multiple people. Only one of the listed maintainers must be authed, there is no way to force a 4 eye/2 user (or more) process for now.