User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > Schedule > Scheduling options for 'Project1'
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\scheduling
This policy setting will allow the update of manually scheduled task dates when predecessor links are created or updated. If you enable or do not configure this policy setting, manually scheduled task dates will be updated when predecessor links are created or updated. If you disable this policy setting, manually scheduled task dates will not be updated when predecessor links are created or updated.