If you wish to prevent CoRoster from making any further changes when you run Auto Assign , you can lock either an individual shift or lock the displayed roster.

To lock an individual shift, click the shift, and choose the locked checkbox and click the update button.

When a shift is locked, a small padlock will show next to the name

You can also lock an entire view (either a week or 2 weeks depending on your view settings)  by checking the lock view button. Only allocated shifts will be locked, allowing CoRoster to continue highlighting unallocated shifts.

Use lock view to lock all shifts and then individually unlock a single shift to let CoRoster find a single replacement for you without disturbing your existing allocations.