How to change scale of time in Source window?

I have looked at quite a few videos, but can’t work out how to stretch or compact the time scale under the Source window of a clip.
I know how to change the scale of the timeline, with the - and + magnifying glass in the toolbar for the timeline. How can I do the same for the clip that is being displayed in the Source window?
(I need this because I want to copy a short part of a clip into the timeline, and need to see more detail so I can place the In and Out points correctly.)
Looking forward to your help,

Hey Jim,
You can’t :slight_smile:
But you can step forward / back a frame at a time using the arrow keys and additionally watch the time code as well. - isn’t that enough ‘detail’ ?

Thanks, I’ll do that.