I installed the Volume control app (by RubberBigPepper) on my N7, but can't enable the equalizer.  I have checked the box that says Enable equalizer/mixer window but still can't get to it.  Long pressing on the icon doesn't get me to it either.  There must be some simple way to access the equalizer, so I would appreciate any help on how to do it.

I have four questions regarding the N7:

1.  At random times, I get a notification in the notification screen indicating the j9pop3@gamil.com signin has failed.  Sometimes, I get 5 or 6 of those same notifications at the same time.  I can access the gmail app, so why do I keep getting that notification?

2.  I cannot figure out how to add or delete contacts when using the yahoo mail app.  Any help?

3.  I've tried repeatedly to use Google Now to use voice to send an email, but I have not yet succeeded.  It does work when I type in the request to send an e mail on Goggle Now.  Any help?

4.  When I set up the gmail app, I deleted many contacts that I don't need.  I recently received a message that I deleted too many contacts, and I now can't delete any more contacts.  Any help?

This is my first experience using any kind of tablet, so I would appreciate any help I can get.