Update- From SaaS V2. We have introduced new Config mechanism.  Follow the SaaS Documentation for this.

You can set default settings for SaaS by editing Workspace.php file
This file is located in /system/models/Workspace.php

When user signup you can pre configure default data and settings for-

• Language when user signup
• SMS templates
• Email templates
• Transaction Categories
• Permissions
• Payment Gateways