The scanner will only scan sites whose control channel frequencies are included in the frequency list for a system. When set to Roam. the scanner will look for the site with the best signal and stay there. If you want to scan multiple sites, set Multi-Site to Stationary. The scanner will scan all sites within range whose control channel frequencies are included in the frequency list for the system. If you wish to be able to select a site or sites, you can setup multiple systems with each one using a different site. You can include all of the talkgroups in each system and assign a different scan list for the talkgroups in each of the systems. That will allow you to select a site or sites by scan list. If there is only a single site in a system, set Multi-Site to Off.