There are two different scenarios in which conflicts can occur and which the system has to check:
Conflict in this context means that, if, e.g., you have modified the plan by moving an operation, in the meantime, another planner could also have done some alterations to the plan. Even in a single-planner surrounding this sometimes happens due to changes made in NAV by another person.
In order to avoid constantly uppopping warnings, conflict management in the Visual Production Scheduler is customizable. The user can decide whether to check
The other way of conflict management is checking modifications concerning calendar or capacity. Conflicts in this case mean that although you might not have moved any operation in your plan, there might still have been other changes, namely ones that affect capacities or calendars. If, e.g., downtimes have been added or calendars have been modified, these changes could well affect capacities in a way that orders can't be processed in time.
Since these kinds of changes don't occur very often and a check should only be done every now and then, we decided to leave the choice to you and let you choose whether these conflicts are to be checked every time the plan is saved or not ("not" being the default setting)
To customize the conflict management options you have to run the table VPS-Setup. Here you find two columns where you can carry out the desired user-specific settings.