I created a new .css stylesheet and want it to be the default theme for all members. This is the one and only stylesheet I have available for members.

The new stylesheet I named High_Lifter.css, the old one being infopop.css.

When I "become a user" they are seeing the old infopop theme even though it is not selectable. In their profile it has "default" selected, but everywhere in the admin panel I have High_Lifter.css checked and named.

Is their a Mysql command or some way I can make High_Lifter be default and change everyone's profile so that is what they see?

First remove all check-marks in your CONFIGURE THEME setting in the Admin panel...leaving only the default one selectable.

Then run UPDATE w3t_Users SET U_StyleSheet='usedefault'

That will set everyone in your database to the default stylesheet, but it will also leave your stylesheet as "selectable" in their Display Properties.

You can alternatively remove ALL selections from your CONFIGURE THEME (including the default)...leaving your users no choices at all (not even to select a default sheet)...and as long as you run the above SQL query and set all users to a sheet that exists on the server (selectable in Display Properties or not!), you will be ok.

Worked great!