Confused about Patterns and Song mode

In the chapter on Song mode the manual says:
“For example the same pattern can be copied
then transposed and parts muted then saved as an alternative version.”

This is exactly what I want to do, but cannot figure out the exact steps.

If I use Add Slot, then any changes made will change all instances of the same pattern.

So using Add Empty Slot, and pasting in a copy of a slot, it is the same behaviour (eg muting a track, affects all the patterns).

If I start in the Pattern screen, and choose Duplicate Pattern or Copy Pattern, then open a new empty pattern, and select Paste Pattern. Now muting a track and swapping to Song mode, I find all the slots and patterns have that track muted.

Apologies if this has already been posted, but I’m desperate to find out how to do this. Thanks in advance.