Can't change password within SourceTree anymore

Somewhere in the later updates, the ability to change an existing password in sourcetree for mercurial accounts seems to have vanished.  I get pull authorization failed as a dialog, and yet no prompt, and the accounts don't seem to have a password field anywhere,  There is no comparable "Authentication" tab in the preferences that matches up with the windows version.  The accounts in the tab on the mac preferences is only remote accounts, nothing that isn't a cloud provider. 

The workaround was to go into the keychain via keychain access and delete the certificate for the repository stored for Sourcetree.  Not exactly an obvious or user-friendly process.