I would really appreciate a simple script function. That would allow to create a simple popup window to request a new password on specific triggers (first login, delay)

are you using database authentication? You can do some of these things if you add columns into the users_db. I am going off of 7.5, I know some of the user table stuff changed in 7.6 but if you can still add columns then you can do things like when you create the user stick a 1 in a boolean column, which coupled with a client startup script that looks for a 1 in that column based on the username, would force the user to change the password. same thing with changing the password. you can write into a date column and in the client startup script test to see if the date in the column for that user is > then 90 days, if it is then force a password change.

I use database authentification. I could do an update statement on the password but I don’t know how to encode it to get the right string to put in the database. It’s why I was asking for a script function. Also, with a script function, it would be possible to change the password with any kind of user source.