Change Scaling via C#

Question

So we have this client using tssharp to connect to a remote computer via RDP. The client needs the scaling set to 125% for some reason. This makes the RDP-Session unusable, because tsplus takes the scaling from the system. So I want to habe a skript that switches the scaling from 125%->100%, then starts a .exe and then change the scaling back. So here I am. My approach was to change the registry via C#. Personally I don't use Windows, so my knowledge is very basic. I can change the registry with my code. It works beautifully. I don't get the registry to reload though. I've tried to broadcast the update, but literally nothing was affected. Then I tried to kill and restart the desktopenvironment (i.e. Windows Explorer). The restart worked, but it didn't care about the new registry. Then I tried power something from microsoft, to automate the clicks. And that piece of s...oftware is absolutely unusable for that. So I'm out of ideas now... How can I make clicks in the Windowssystemsettings with c#? Is there any kind of library or something like this? I've tried the system32 api. Didn't work. Or do you have another idea on how to approach the problem? Like I said I pretty much know nothing about windows, so any idea is welcome. I literally just want to automate 8 clicks and I'm not able to do that.