problem with unplanned auto-zoom - Samsung Duos phone camera

Samsung Galaxy cell phone Duos GT-I9082; Android OS 4.1.2
The camera zoom function (1x - 4x) slides to 4x without any command, and will not hold when manually drawn back down to 1x via touch. Repeats slide to 4x as many times as attempts to correct and hold down. Does not occur with every use of the camera function (maybe 60%). To clear it, sometimes, I must switch commands (e.g. to photo folder review, or specialty commnds (flash, exposure, etc.) This sometimes works, sometimes not. Backing out to main menu and starting camera function again sometimes works. Latest verion of software is downloaded, without result. Is this unique to my phone, or commonly occuring, with a solution?
Also, randomly, an audio volume control bar appears over image of stored photos (mute to full slide), only goes away with patient waiting, or by switching back to live camera, then back to photo viewing. The bar control is active, but irrelevant to the situation.