If change tracking is enabled, you can only make changes in the model when a Change Note is active. Each user's active Change Note is stored in the registry of their computer so that each user of a model can have a different active Change Note.
To make a change note active
Right-click the Change Note you want to make active, and then click Set Active.
Alternatively, from the Change Tracking toolbar:
• In the drop-down list, select the Change Note you want to make active.
• Click the Set Active button, and then select the Change Note you want to make active.
If change tracking is enabled, changes you make in the model will now be recorded against the Change Note you have made active.
Set Active button, and then select the Change Note you want to make active.