Hey TrixieG123,
If we understand correctly, the folders you open are not opening in a new tab even though you set the setting correctly. Try starting the Mac in safe mode and see if the issue persists.
Is it happening to all folders or only certain folders?
"On your Mac, choose Apple menu > System Preferences, then click General .
Click the “Prefer tabs when opening documents” pop-up menu, then choose an option:
- never: Open folders in a new window, not a tab.
- in full screen: Open folders in a tab only when you’re working in full screen.
- always: Open folders in a new tab."
Change how folders open in the Finder on Mac
How to use safe mode on your Mac
Please don't hesitate to let us know if you need additional assistance.
Thank you for using Apple Support Communities. Have a good one.