To change things in your account, you first need to access the right page. You can do so by clicking on your name, and then on 'My account'. Or you can paste the following URL in your search bar:
Next, you will arrive on the page shown below. Here you can adjust various details, such as the first name, last name, phone number, and the email address where invoices are sent. You can also disable two-factor authentication here.
You can also edit the company information if you go to the tab 'Company'
Here you can adjust information like your company name, which timezone you are in, your country, city and your address.
You can change your password on either one of those pages.