BillR [MVP] wrote:

Try a new profile created via the Mail icon in Control Panel then
open your old PST and copy the items to the new one.

Creating a new mail profile doesn't automatically create a new PST, although
it appears you believe it does. There will be no "new" and "old" PSTs for
the OP to copy between. There will be just the original PST which they can
use in the new profile.
--
Brian Tillman