How do I set standard authentication for a user

[Walter Griffith]

I use MySQL 8.0.12 on a macOS 10.13.6 Apple laptop. My Workbench version is 8.0.
I have MySQL databases that must be accessed by R scripts and the RMySQL package apparently doesn't like SHA2 authentication. I logged into Workbench as root, went to Management/Users and Privileges and tried to change the Authentication Type for the proper user. The screen suggests using the "Standard" authentication type here, but Workbench only allows "caching SHA256 Password" as an option (it's greyed out and I can't scroll to any other method). How can I use "Standard"???