You cannot change the notification interval. When an alarm is first triggered, you receive the first notification right away. If the condition has not been cleared, you will receive a follow-up notification every 60 minutes.
If you have any low-priority alarms where you don't want hourly notifications, you can use a virtual output to create a "one-time" alert, which will also allow more critical issues to send alarms since the Apex is limited to only sending notifications for a single alarm condition at a time. See my Apex Alarms tutorials for more details and example programming:
https://www.reef2reef.com/ams/neptune-apex-programming-tutorials-part-6-alarms.707/