The short answer is:  Yes.

 

You can modify almost all the contact information you provide.

 

However, be advised that information that has already been pushed to an Invoice (meaning if you already made a payment) will not be possible to change as those are permanent records.

 

Invoices are taking their values from the information you provide, and once an invoice is being issued, it obtains the values that are current in the client information at the time of the invoice issuance.

 

Once you register,  you can modify your User Details as shown below: