Visual Studio adding Signatures (Selfcerts) to applications to run in Excel

Self Cert:

• Office 365 32-bit (Subscription based or Click-to-Run version of Office 2016 / 2019)
  C:\Program Files (x86)\Microsoft Office\root\Office16
• Office 365 64-bit (Subscription based or Click-to-Run version of Office 2016 / 2019)
  C:\Program Files\Microsoft Office\root\Office16

From:https://docs.microsoft.com/en-us/visualstudio/deployment/how-to-add-a-trusted-publisher-to-a-client-computer-for-clickonce-applications?view=vs-2019

To add a certificate to the Trusted Publishers store under the trusted root

Obtain a digital certificate from a CA. (WE are using a self cert)

n windows - search for "Manage user certificates"  or "Certificates"

Export your selfcert:

Suggest dumping it in your CODE folder.

Export the certificate into the Base64 X.509 (.cer) format. For more information about certificate formats, see Export a certificate.

search for CMD from the start menu - right click and run as administrator

Locate certmgr.exe

"C:\Program Files (x86)\Windows Kits\10\bin\[current windows version]\x86\certmgr.exe"

From the command prompt on client computers, run the following command:

certmgr.exe -add certificate.cer -c -s -r localMachine TrustedPublisher

https://docs.microsoft.com/en-us/dotnet/framework/tools/certmgr-exe-certificate-manager-tool

To add a certificate to the Trusted Publishers store under a different root

Obtain a digital certificate from a CA.

Export the certificate into the Base64 X.509 (.cer) format. For more information about certificate formats, see Export a Certificate.

From the command prompt on client computers, run the following command:

certmgr.exe -add [cert name.cer] -c -s -r localMachine Root

certmgr.exe -add [cert name.cer] -c -s -r localMachine TrustedPublisher

Note it seems typical VBA applications and back end office come in at the personal certificates where the selfcert was stored: