Editing the Customer Details didn't work for me, nor trying a new browser nor clearing cache. The only way I found to solve this is to open the invoice, then add or edit the name in the Billing and Shipping address boxes on that open invoice screen, you can edit the address too if necessary, then click Print or Preview and you should see the correct name and address in accordance with your edit. If you don't, check your edit on the open invoice screen. If you still don't, it's probably because it's difficult for me to explain this here, but I hope it's clear and works for you. It will only change the invoice you are working on, so if others are not displaying the name and address correctly, you'll have to open those and edit them too.