Background image for all users

Hello

I need to set up a background image for all users to differentiate the database and companies they are working on.

The manual process (as explained in a previous post) is impossible to manage and is not a solution for us.

I have tried to update OUSR.wallpaper and OUSR.wllpprdsp but it doesn't seem to be taken into account.

Has anyone traced which field is also required ? I suppose that there is another background link to another table.

Thanks for your help

Fabrice