Limit per hour override limits the number of alerts that you receive per hour.
It is possible to limit the number of alerts to 5, 10, 25, 50, 75, and 100 per hour, or choose the option Unlimited with which you’ll receive the real number of alerts per hour, no matter the number.
If you wish to increase the alert limit per hour of your existing alert, click to edit the alert, and at the bottom, you will notice the Reached limit? option.
Click on that and you will be able to set the number of alerts per hour you wish to receive (Unlimited, 5, 10, 25, 50, 75, 100).
You can also set up the limit while creating queries. The procedure is the same.