1. In File Explorer, right click an appx that you've signed with a test cert and choose Properties from the context menu.
2. Click or tap the Digital Signatures tab.
3. Click or tap on the certificate and choose Details.
4. Click or tap View Certificate.
5. Click or tap Install Certificate.
6. In the Store Location group, select Local Machine.
7. Click or tap Next and OK to confirm the UAC dialog.
8. In the next screen of the Certificate Import Wizard, change the selected option to Place all certificates in the following store.
9. Click or tap Browse. In the Select Certificate Store window, scroll down and select Trusted People and click or tap OK.
10. Click or tap Next. A new screen appears. Click or tap Finish.
11. A confirmation dialog should appear. If so, click OK.