If you had been previously told to stay out of Wal-Mart and returned, or were told to leave and did not; then you were trespassing.
If you are trespassed and want to know if that can change, contact Wal-Mart and ask.
If you have been trespassed from Wal-Mart and are unsure if you were trespassed from one Wal-Mart or all Wal-marts, it likely depends on the facts. Best to stay out of all of them geographically close to whichever one you were naughty in that resulted in a trespass warning/notice.

