how to save "record for fixed length of time" setting?

[LoyaltyCIO]

I was frustrated because my camera would often capture delivery truck arrival, but never record driver taking package to porch.  Discovered in search that I should configure camera to record for fixed length instead of record until activity stops (often truck appears not to move, but driver exits other side). I found the \device\edit mode\edit rule\record settings\and click the radio button to record for fixed length of time, but can't find way to save new setting?  No matter how I navigate away from the setting it seems to lose or forget the setting?

[jguerdat]

There is no "save" on that page. Just go back to the previous page and use the "Save" button at the bottom when you're done editing your mode.