Hi there,
How to make start menu on windows 8 open on the display that i'm currently using instead of aleays on the main display? (Also using start menu 8

Have a look at this thread, I think it answers your question.
http://www.displayfusion.com/Discussions/View/windows-81-open-start-menu-on-monitor-it-was-clicked-on/?ID=665f9d60-da8c-41c6-af0b-62e3659f832e