Hello Stirling-commerc,
Welcome to the Community page,
If you are referring to the changing the company's old address then you can do this be following the below.
Cog wheel- account and settings> company> contact information you can change the address in there and also if you go to the cog wheel again> custom form styles> click on the template you use>content> click the top box right hand side> click address and if showing wrong address you can change it to the right on> done.
If you are referring to a customer's address needing to change their old address if you click on sales> customers> click on the customer in question>edit top right> change the address> save
If your referring to a suppliers address needing changed from their old address if you click on expenses> suppliers> click on supplier in question>edit top right> change the address> save
