Thanks to Aderson Oliveira for this:
'm usually concerned to give user advise to run scripts on their database, but you could do something like this:
update users
set updatePassword = 1
where userid > 10
I add userid greater than 10, but you can adjust that so you don't force host nor admin users to have their password reset.
For security (and disclaimer) I would recommend a full site and db backup to prevent potential misuse.
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Setting updatePassword = 0 will turn off the requirement to change the password on login.
The test for userid>10 is to eliminate users with those low numbered UserIDs. This will exclude some superusers and administrators. You can did you the Users table to figure out which you should really exclude.