Want to switch map sources? Unlike some people think, you don't pick a map source and be stuck with it for life. Many people switch between them often.
This is an especially popular topic since MyTopo stopped working and you are advised to switch to USA Topo maps.
First, go the Maps Control Panel. You can push Menu->Maps to get here, or push the "Layers" button on the top action bar.
The most recently used maps are there in a drop down.
But you can choose "Choose Map Source" to get even more choices.
Under 'US and Canada" you can choose "USA Topo Maps". Please use this instead of MyTopo.