chosen courier being changed on all simple delivery items already listed

Hi

I have a large item over 61cm so can't use royal mail as I would normally  do.

When starting a new listing I changed the courier to Evri and excluded Royal Mail because they will do  larger size parcels

A message comes up

"Changes will be applied to all active Simple Delivery listings. "

This changed all my already listed items

Anybody have any ideas on how to stop this from happening