Alter the play speed on a Ken Burns effect

Quick question.

I have set a short test Ken Burns effect on an image, I'd like to slow the transition down as it plays too fast for what I want.

Any kind soul tell me how I can alter the speed of playback? I have looked at time remapping but I am unsure if it's the right thing.

Thanks in advance.

Update. Curiously when I try time remapping it (sort of) works, but in the edit tool, I no longer see the keyfreames I set up for the Ken effect. Why is that?