To archive all completed tasks only in a task folder in Outlook, please do as follows:

1. In the Tasks view, click Folder > New Folder to create a new task folder.

2. In the opening Create New Folder dialog box, (1) type a new name for the new task folder in the Name box, (2) click to highlight the Tasks folder where you will place the new folder in the Select where to place the folder list box, and (3) click the OK button. See screenshot:

3. Click to open the task folder where you will archive completed tasks only, press Ctrl + E keys together to activate the Search Tools, and then click Search > Completed Tasks. See screenshot:

4. Now all completed tasks are found out. Select and drag all of them to the new created task folder on the Navigation Pane. See screenshot:

5. Click File > Info > Tools > Clean Up Older Items (or File > Info > Cleanup Tools > Archive) to open the Archive dialog box.

6. In the popping out Archive dialog box, (1) check the Archive this folder and all subfolders option, (2) click to select the new created task folder in below list box, (3) type Tomorrow in the Archive items older than box, and (4) click the Browse button. See screenshot:

7. Now the Open Outlook Data Files dialog box comes out, type a name for the new archive file in the File name box, and then click the OK buttons successively to close two dialog boxes.

8. In the popping out Microsoft Outlook, please click the Yes button to go ahead.

So far, all completed tasks you moved to the new task folder have been archived manually.

Note: If you need to set AutoArchive settings for the new task folder, please right click the new task folder, select Properties from the context menu, and then specify the AutoArchive settings in the popping out Properties dialog box. See screenshot:

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