To enable or disable the Gantt module's Save Production Plan control:
Go to Setup > Site Configuration.
Click index #2 (Step 2 - Define Departments).
Click the index number of the department you for which want this featured enabled (or disabled).
In the department's General tab select the Save jobs in gantt check box to enable this feature (clear the check box to disable the feature).
Click Save Changes.
NOTE
When a Gantt includes a mixture of departments (departments which have the setting enabled + departments which have this setting disabled), this control won't apply the planning to the jobs of those departments which don't have the Save jobs in gantt check box enabled.
Related articles
Gantt Module Orientation (old Gantt)