Gsimonelli,
You cannot overwrite the default "Style" ( found under the Style Tab in New Song Window) Templates in Studio One. However, you can create your own custom templates; configured to your specific session needs.
If there is a particular Song setup you use again and again, it can be helpful to create a template. To do so, first create a new Empty Song. Next, configure the I/O and create and configure all Tracks, and virtual instruments, effects plug-ins, and any other aspects of the Song that you need in your template. Then, in the File menu, select Save as Template.
Type in a title and description, choose an image for the Template icon, if you like, and select OK. You can also drag an image from Windows Explorer or Mac Finder onto the image icon to use that image. The exact current state of the Song is now available as a template in the New Song creation menu.
This custom template will now be available when you select " Create New Song " and can be found under the " User " Tab on the New Song Window. This tab is setup for quick access to your own customer templates without overwriting the core templates that come preconfigured for Studio One usage.