For your convenience, It is possible to set a default value for the 'available in distribution list' checkbox when adding a communication type.
To do this, go to the Communication Categorisation reference data table, right click a communication type to maintain it, then tick "Default in Distribution List?"
Please note that the protected communication types with the lock next to them cannot be changed using the interface. If you want the default value for one of these communication values to be changed, you can request this on the HelpDesk and the ChilliDB support team will do this for you.