If you need to modify the important information of your establishment, you need to access to your Back Office.
Specifically you have to go to Configuration>your Business.
By clicking on "EDIT" you will be able to modify some information, such as:
Name of the establishment.
Language.
You can add you Logo on your final ticket.
You can set a personalised message on your final ticket.
If you still need to modify other details, for example your Vat Number, please contact Customer Support.