Select the performance monitor you want to configure for the selected devices, then select how often (in minutes) you want to collect data in the Data collection interval (mins) field.
Select All to have WhatsUp Gold collect data on all instances of that type on the selected devices, select None to stop collecting data for all instance of that type on the selected devices. For Interface, Active collects data from interfaces up at the exact time of the poll. Default for Ping polls the default interface you select in Device Properties > General.
You can select individual data type instances for each device at Device Properties > Device Properties - Performance Monitors.