Hi Ron,
Looking at the screenshot you have provided it looks like you have a global theme setting enabled
[upl-image-preview uuid=86d297cb-9b74-4fae-bcd5-9b3758506b9f url=https://discuss.openlp.org/assets/files/2025-01-07/1736263327-343986-image.png alt={TEXT?}]
You can see this by the missing service level theme. In order to be able to change the theme at the item level you need to select Song level themes.
[upl-image-preview uuid=d62e0587-23af-424b-afa1-d1f3e9ee0ec4 url=https://discuss.openlp.org/assets/files/2025-01-07/1736263481-513588-image.png alt={TEXT?}]
[upl-image-preview uuid=d078374f-c18d-4800-9bdd-36b72e175197 url=https://discuss.openlp.org/assets/files/2025-01-07/1736263556-725312-image.png alt={TEXT?}]
I'm using 3.1.3, but I'm fairly certain this is your problem.