Selecting issues

When I’m selecting a piece of the outline of an object that I want to delete,
sometimes it turns bright white and is delete-able, but other times it only turns a shade of gray and is not delete-able.
What makes the difference?

Which tool are you using to select?
Which window are you selecting in?

Either the select tool or the contour editor.
The camera view.

Try going into the preferences and on the “Camera” tab - check the “Select Tool Works on Single Drawing” option.