You can store your personal business details using custom variables. In order to add the necessary variable, please, do the following:
1) Go to "Advanced Settings > Template Variables"
2) Click the New button
3) Enter your variable name (\MY_ADDRESS\ for example or \MY_VAT\ ) into the name field and the content this variable represents into the content field. Then click OK.
4) Go to "Business Settings > Templates". Open the necessary template and add the new variable to this template.
Also you can add your address or VAT manually. Simply open the necessary template and enter the data. After saving the template, the entered text will be present in every invoice issued with this template.