Automatically enable/disable data mobile on galaxy s3 i going to turn on my data to use internet, but the Wi-Fi symbol going on then off what should i do...
please help me...
my phone: Galaxy S3
Your initial question seems a bit vague, so I'm goign to assume that you're asking why when wifi is turned on, cellular data goes off. If this is not the question you are asking, please ignore my answer.



That is how android is designed to handle data. When Wi-fi is on, Mobile Data does not get used. 

If you want to keep mobile data active even while wifi is on, go to Settings > developer options > Under networking section you'll find an option  "Cellular data always active". Turn that on. This does not mean that cellular data will be used when wifi is on. It only means that automatic switiching between wifi and cellular data will happen a lot faster.