Thank you for keeping us updated about the outcome when trying the steps above, NelsonImprvmnts.

When performing the recommended solution, I suggest you'll have to sign out and sign back in for the changes to take effect. However, if you're still unable to turn off the Dark Mode theme, I suggest contacting our Customer Care Team. If other users are experiencing the problem, they can open a ticket for further investigation.

To reach them, click the ? Help button at the top-right corner and select Contact Us to talk with a live agent. Ensure to review their support hours to know when agents are available.

If there's anything else you need help with, please let me know by commenting below. I'm always here to answer any questions you may have. Take care.