User Activity

Drives me nuts because I need the camera to sit in its tripod and film continuously.  My presence distrurbs the scene.  How and where do I go to change video recording to go longer than 15 minutes?
I just purchased a new SX700 and have taken several videos over the last 24 hours.  In each of these videos, some short and others long, all of the audio is out of sync.  Am I missing some setting or should I return the camera for a replacement?  Thi...