Notifications
If you'd like to receive your checking balance updates from Digit less frequently (or not at all), just message the word Notifications to the number that Digit texts you from.
You can then choose to keep the updates to be sent Daily, Weekly, or Never. If you choose Weekly, your checking balance will be sent every Monday.
To adjust those settings down the line, just message Notifications again.
Push notifications
You can now enable push notifications if you'd rather see updates as pop-ups instead of in texts. See: How do I enable or disable push notifications?