On my invoice, I want to put sellers address. Currently, it's showing store address. How can I do that?

Store Hippo allows you to design your custom invoice template or make changes to the existing templates.
You can edit the invoice templates in Settings > Invoice Templates section under StoreHippo Admin Panel. 
Click on edit on Invoice. Make the changes in the template and save it.

Please refer to the following link for more information:
https://help.storehippo.com/topic/invoice-templates