The Constraints Type and the Constraint Date boxes are grayed out for Manual Tasks. Manual Tasks have the main purpose to not have its Start, Finish dates and Duration modified by the Project Plan 365. For this reason, manual tasks should not have any kind of constraints.If you want the app to calculate dates from scheduling inputs, switch the task to automatically scheduled and review the result.

Check the Task Mode field first. Manual tasks can retain blank or descriptive date values. If you want Project Plan 365 to calculate the dates, switch the task to Auto Scheduled and review the calculated result.

If you don’t want to level, you can try other ways to resolve overallocations.
- Replace one resource with another who is available to work at that time.
- Replace more skilled resources on critical tasks early in the project. A more skilled resource is likely to get the same job done in less time.
- Change a task link so that some tasks start at the same time.
- Spread the workload out by Increase the duration of tasks with overallocated resources.
- Reduce workload by reducing the amount of work required for completing the task.
- Change the working hours of resources to shorten the duration of tasks.
- Reduce the duration of tasks, especially critical tasks that directly impact the project end date.
- Check that resources are not working during non-working time. If a resource is working during non-working hours, Project will show them as overallocated.

For detailed information about Resource Overallocation, see the Resource Overallocation Online Help Article.

To level tasks for certain resources, go to “Team” menu and click the “Level Resource” button. In the “Level Resources” dialog, select the resources for which you want to level tasks and click the “OK” button. A summary of how Project Plan 365 fixed the overallocation will be displayed. Click the “OK” button for the changes to be applied. For detailed information about Resource Leveling, see the Resource Leveling Online Help Article.

To level only the selected tasks, go to “Team” menu and click the “Level All” button. In the “Resource Leveling” dialog, the “Selected tasks” option and click the “OK” button. A summary of how Project Plan 365 fixed the overallocation will be displayed. Click the “OK” button for the changes to be applied. For detailed information about Resource Leveling, see the Resource Leveling Online Help Article.

To level the entire project, go to “Team” menu and click the “Level All” button. In the “Resource Leveling” dialog, the “Entire Project” option and click the “OK” button. A summary of how Project Plan 365 fixed the overallocation will be displayed. Click the “OK” button for the changes to be applied. For detailed information about Resource Leveling, see the Resource Leveling Online Help Article.

The “Set Task Mode” functionality gives you the option of deciding how much control you want over task scheduling in a project. The Task Mode field indicates whether a task is scheduled manually or automatically scheduled. The default scheduling mode for new tasks is configurable in File > Options > Schedule.

The Task Mode field indicates whether a task is scheduled manually or automatically, which gives you the option of deciding how much control you want over task scheduling in a project.