Microsoft PowerPoint themes are missing in design tab but present in my Office install folder

Copy the .thmx files into your per-user Document Themes folder so PowerPoint registers them as custom themes instead of browsing to the Office installation folder each time.

Add all installed themes to the gallery

1. Close PowerPoint.
2. Press Windows key + R.
3. Enter:

      %appdata%\Microsoft\Templates\Document Themes
   

4. If Document Themes does not exist, create that folder under %appdata%\Microsoft\Templates.
5. In File Explorer, open:

      C:\Program Files\Microsoft Office\root\Document Themes 16
   

6. Copy the desired .thmx files into the per-user Document Themes folder. Do not move or delete the originals from Program Files.
7. Reopen PowerPoint and expand Design > Themes. The copied themes should appear under a Custom heading.

This uses the same local Document Themes location PowerPoint uses when Save Current Theme creates a .thmx file; themes saved there are automatically added to the custom-theme gallery.^1^ Microsoft also identifies %appdata%\Microsoft\Templates as the user template area.^2^

There is no documented bulk-import command in PowerPoint. Copying the files to the user theme folder avoids repeating your existing Browse for Themes workaround.

If a copied theme does not appear

Use PowerPoint to save that particular theme into the correct location:

1. Select Design > Themes > Browse for Themes.
2. Open the required .thmx file from Document Themes 16.
3. Select Design > Themes > Save Current Theme.
4. Keep the default save location and select Save.

PowerPoint then adds it under Custom.^3^

About the disabled “Enable Content Updates from Office.com” option

That option concerns downloadable online content, not the local .thmx files already installed on the computer. To enable connected experiences:

1. Open File > Account.
2. Under Account Privacy, select Manage Settings.
3. Enable the connected-experience setting that allows Microsoft 365 to download online content.
4. Restart PowerPoint.

Microsoft documents this as the control for experiences that search for and download online content, including templates.^4^

If those privacy controls are unavailable or locked, they may be managed by the institution providing the student account. In that case, the school’s Microsoft 365 administrator must change the policy; the local custom-theme method above does not require online content updates.

References

1. Create your own theme in PowerPoint | Microsoft Support
2. Where are my custom templates? | Microsoft Support
3. Add color and design to your slides with Themes | Microsoft Support
4. Connected experiences in Microsoft 365 | Microsoft Support