Unwanted keyframe appearing

In recent weeks, when I extend the exposure of one or more layers, a keyframe automatically appears at the point I extended it to. Did I switch on some setting that does that with out realizing it?
~ Justin

There is an option under preferences-timeline-paste/drag and drop. - add keyframes at beginning and end.
I tried both with and without, without result.
Thats to say , for me, no keyframes added.
Looking forward for an explanation.


I tried all the paste options, and I tried Flash shortcuts and TB shortcuts, and I was never able to make F5 (Extend Exposure) add a keyframe as well as extend the exposure. I can make drags and pastes add keyframes, but not extend exposure.

Can you reproduce this behaviour on a specific scene file?