Freq on Atheros AR9888/RB911G

Hello!
Why isn’t the list in Wireless - skanner updated when you start it over again?? Have change freq on a antenna nearby and it stills shows up With the old freq on this list!

Is there any how-to-do pdf files on the net, which a newbeginner can use to program/setup a New antenna??

Regards
Kåre!