When in any mode, to take a still photo press and release the large shutter button.
To take a video in any mode, press and release the smaller Motion button to start recording, then press and release it again to stop recording. The sound will always be on when recording, unless you go into the menu settings and turn it off.
How old is the camera?
The small microphone holes are on top of the camera, just behind the lens - check that they are not blocked with any fluff, etc.
There isn't any volume control. It will only record sounds close up.
If you plan to record a wedding ceremony at a distance, this camera will not record the audio from the proceedings.
Enjoy the wedding :)Pete.