Use the Monitor Thresholds dialog box to monitor all of the open project's thresholds at once.
Use original threshold monitor windows: Choose to monitor all thresholds with their original monitor time windows.
Use new threshold monitor window: Choose to specify a new time window to monitor all thresholds. To select a new time window to monitor, click 
in the From Date and To Date fields, then click Monitor.
From Date: To specify a start date for the new monitor time window, click .
To Date: To specify a finish date for the new monitor time window, click .
Monitor: Monitors all thresholds according to the options you specify.