Default EP by user

Hi Guys ,

I have a small question for you, how can i assign an EP by user or by group? 

I know that there are several portals in Dynamics AX EP (Sales. Purchase, Finance, Employee services...) but in my case, I want that everybody goes to Employee services.

I find that is linked with security duties because the user that they have just timesheet role, they go directly in there but not for purchase agent or project manager...

Thanks