Many schools are at different levels of collaboration. This setting is useful if you choose not to fully collaborate on a plan but have designated teachers creating plans to share with their colleagues. Instead of using the plan owner using the 'Share' feature, other teachers could instead open another teachers plan and create their own copy to work off when this setting is switched on.
Please note that only admin users have the ability to switch on this setting (contact us if you are not sure who your school admin is).
1. Go to Settings in the dark blue section at the top of the page.
2. In Setup click on Details to edit the details of the school. 
3. In the next page that loads look for the option Allow Plan Copy From Any Teacher and click on the tick box besides it to switch on this setting then click Save. At any stage you can come back to this page and turn the setting off.