I am working on a financial product. Re designing the dashboard/summary page also including the top menu, so I have some doubts if should I put the "Sign up" or "Log out" button at the right corner on the top menu? At the moment we are putting this button under "my account" and the user can find the button on the submenu, so is "hidden". 

Paypal has the Sign up button at the right top corner, also for example in my personal bank account they also put this button visible. I think is a good practice but I don't know why, can you please if you know explain me the reason.