Start GMail, select Settings then choose the GMail account you want to change, select Labels to notify - which brings you to about 16 seconds into this video:
[youtube]http://www.youtube.com/watch?v=OH185h64PfA[/youtube]
For the GPS issue: grab another GPS app and check if that works - if it does, the problem is with Waze.
There are several GPS test and monitoring apps available in the Marketplace.
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Giraffe: a ruminant with a view.