When I apply formatting changes to a single line of a numbered or bulleted
list, Word applies the change to the entire document instead. I then have to
choose "CTL +Z" in order to undo the operation to get the results I want.

An example of this would be when I want to change the font color or the
indenting amount of a single line in a numbered list. I highlight the line
that I want to change and then select the change color button (for instance),
but the change is first applied to the entire document. If I press CTL + Z
at that point it reverses the change on all except for the hightlighted text,
which gives me the result that I had wanted but with a lot of extra bother.

It is very annoying to have Word keep applying these changes to the entire
document each time, instead of to the highlighted text only. How do I stop
Word from behaving like this?