Hi Dion,
Thank you for your purchase.

Yes. I will give you an instruction which table in database you have to modify and which content, but you need to be very careful when you update this table because can cause not proper working of plugin if you delete or add something else.

In database, you have to find wp_options table .

In your case it is possible to have different prefix but it will be ended it like your_prefix_options. 

Then you have to find option name amelia_settings in this table.

When you find that you have to edit that property and to find in JSON file string redirectURI and you probably find this :

 and you have to replace it with this

So basically you need to replace newsite.com with youroldsite.com and it will be shown in Google settings properly. Please note that if you use https you will need to update it also in redirectURI option.

When you finished this please check is the same URL from “Redirect URI” field and on "Create OAuth client ID" section in field Authorized redirect URL's.

Best regards.