Well this happened :
There’s no more button to change the quality preset and I’m pretty sure I’m stuck on the “Epic” one.
Not sure this happened before or after reinstalling UEFN to my SSD.
Top Right of the Viewport > Settings > Engine Scalability Settings.
Wtf, answer has been set to be the solution automatically 
Thank you though, I changed it and the parameter came back inside the viewport for some reason 
Yup, I believe there was a way to stop it from hiding, but I can’t seem to find it anymore, sorry!