Updating your account name is really simple, to do this, you first need to move your mouse cursor to the Account tab (found at the top of the system).

From here a menu will appear and you will see the option "Account Details", go ahead and click on that option

Now, you should see the screen below

This shows you all of the main details about your account, from the name to the address details and beyond. 

From here, click on the little pen icon next to Company Name.

This will then change the Company Name to be editable as shown below

Simply update the name and click on the tick icon and that is it - you've now updated your company name!