You can create new account types when creating a new accounts.
Currently, the account types of all accounts cannot be edited once set, so when creating a new account be careful when choosing the account type.
Navigate to Settings > Accounting > Account codes menu and click on the Create new account code button.
Add the new Account name, VAT rate and tick the check boxes to show in purchases or sales as appropriate. Click on the Add new account type button.
You will then be able to enter a new name in the New account type field and select an appropriate Category. The categories are fixed and cannot be added to or edited in any way.
Hit the Save new account button to complete.