In the global setting field, i have removed choice in the checkbox.
Howerer in the courses setting filed , the checkbox is forbidden ，the teacher can't modify the state, even the admin accout can't .
I really can not understand it , thank for everyone willing help me .
Hello there, @Captaingz ...
Hope this helps a bit. Let Community members know if you have any other questions about this...thanks! Be well.
Thanks very much @chofer
The problem is that I haven't added any JS or CSS file to the system. In order to find the causes of the error, i made a test in the test environment and it's OK. This picture shows my setting , it will appear ' View File' link if I ever uploaded the file.
The more stranger of it is that some courses can still modify the check-box and the other courses can't. After the global setting, the course setting displays the different states，as follow:
Could you give me more suggestions about the problem , thank you very much.
Hello again, @Captaingz ...
The screenshots you provided in your initial post and your reply appear to be from the "Settings" screen at the root account level.
By chance, do you have a sub-account structure set up for your school's Canvas environment?
If so, go to one of your your courses where you are unable to modify those settings, and then in the course "Settings" screen, look to see which sub-account that particular course is assigned to. Go to that sub-account, and then click on the "Settings" screen for that sub-account. Are any of the settings within that sub-account preventing the option of changing things at the course level?
Keep us posted...thanks!