What is your undo tablespace now?
You have not changed your undo tablespace as suggested before by one Pando and others.
You are still using UNDOTBS1 as your undo tablespace.

You have not executed the queries correctly.
I requested information for UNDOTBS1 but you have executed for UNDOTBS

Make the UNDOTBS2 or any other newly created tablespace as
current undo tablespace and make your SPFILE also recognise by using scope=both.

Revert with details.