Hi peter

There probably is a long post or white paper, but just to get you going a couple of notes.

In the sql server admin, create a new sql user. Give it a name like dfusr or the name of your application. Set the password to something hard to guess and make a note of it.

Then give this user appropriate rights for the database that you are using (tick all the boxes first, once it works and you do some more research change to min. Required.)

Then on the clients, untick the trustee user, and instead type the user (dfusr) and your password.

This should solve the credentials issue.

It does rely on sql browser, tcpip and firewall settings already being done.

When you have set it up once it’s a hand full of settings that is quickly done, but a first time and take some time to figure it out.
If stuck, google like ‘sql express network client access’ or so.

Cheers
Marco