You have full control over the look and feel of the invoices that you create in Actionstep. You can change these by editing the source MS Word DOCX template and inserting merge fields for the live data. Actionstep ships with some default templates which you can use as-is or modify to suit your needs.
Attached are some sample invoice template files.
To upload these files go to your Administration > Document Templates > Bill/Expense Templates*
If you are replacing an existing Template, click on the Template name and just replace the existing file. If you are adding a new one - click Add New template
In this same screen you can specify which type of transaction the file is for and if it is the default selection - in the screenshot below, the template loaded will be available when creating a Client credit or Invoice (it will not be available for any other function). It will also be the default when generating the Document (any others will be available in the drop down list).
* Depending on your Accounting setup Bill/Expense may be referred to by different names