You can change the status of your issue by clicking on the edit button  in Issues panel. 

You can enter the new information in the specified fields. As you click the Assign button, it will set the issue in a new assigned state. The color of the flag will change to orange. 

The next status is Send for Review. At any time you can always go back and send back the issue to its previous state. The color for the flag will change to yellow. 

The last state for the issue is the Approved state. Once you approve the issue, they will be closed and changed to a green flag.

By default, only opened issues are displayed on the model and the Issues panel. If you want to display your closed issues, please make sure you remove the Open filter in the State option.

You can also create your own workflow and status by using custom Forms.