Mr. Know it all

Basically your box is junk.

Get rid of it and buy yourself a Channel Master CM 7000 box.

Most of the junky boxes will update channels, but when you move the antenna to receive one channel and do a scan, it will loose all the other channels that it no longer receives.

You need to buy a box that will store all the channels you found on the first scan and can repeat scans without loosing the others.

The cheap boxes don't do that.