Need a little help. I have a 16 gb sd card but main memory keeps going lower and lower. Everything I download goes to my sd card and when it installs it doesn't give me an option where to install...I'm assuming its being installed on sd card but my main memory is down to 117 mb. When I go to apps installed on main memory the ones I download aren't there so doesn't look like its going to my main memory but something has to be using it up