Connexions 2 displays contacts and groups only in the default account. To set the default account, go to the Settings app > Mail, Contacts, Calendars > CONTACTS > Default Account. If the setting is not displayed, iOS automatically sets the default account, so you don’t need to set the setting.

The source is a place where data of contacts are stored. A source has one to one relationship with an account. Examples of source types include Local (DB on your device), CardDAV, and Exchange. If you use contacts on iCloud or Google on your device, the source type is CardDAV. If you use contacts on Exchange Online of Office 365, the source type is Exchange. You can check the source type of the default account on the Source Type setting screen of Connexions 2.

Connexions manages groups (including the order of groups and group icons) for each source, so if you change the default account setting, not only contacts but also groups displayed in Connexions will be changed.