Menus and navigation are easily managed with CMS5, if you pay close attention and remember the cardinal rule of easy navigation: keep it simple! When you start trying to trick the system to create menus and flows that aren't natually part of the system's design you can get into complicated situations.

Most pages have a simple menu element that will allow you to manage that page's menu configuration from within the page's edit screen. See page, click edit, scroll down to Menu settings. It's usually that simple.