Hi there,
Welcome back to the Community. I'd be glad to answer your question about updating your sales tax codes in bulk.
You'll have to manually update the tax codes one-by-one for now. I know how beneficial it would be for you to have the option to bulk edit the tax codes. I encourage you to send this as feedback over to our engineers. You can do this by clicking the Gear icon and looking for Feedback.
Let me know if you have other questions. I'll be happy to help.