This will demonstrate creating custom Visio Templates in SI. Some examples of why you would want to create a custom Visio Template are:
You will want to make sure that you have the following Project Setting set to "Never":
You will also not want to check the "Populate company logo on title block" option when creating a Visio file using your custom template:
C:\ProgramData\D-Tools\SIX\Templates
This will open a new window where you can then make your modifications, e.g. remove the existing D-Tools logo and add your own.
In order to share customized templates with other users, you must give them a copy of your .vst files and they must place them in the following folder on their computer: C:\ProgramData\D-Tools\SIX\Templates