Hello Nick,
no need for apologies, I appreciate your help 
The first image shows exactly what I mean. To be fair this also happens when using the "usual" logon screen, I simply don't know where to set a default parameter for every user. This really bugs people a lot, as well as not being able to switch languages when they only have one user / one client per system. They would have to go to their profile and change the parameter, but that kills the feeling of a benefit by using SSO and really complicates my project.