The threshold time, or SLA, is a useful tool that can help increase your kitchen station's efficiency. To modify it:

Step 1: Visit Setup > Location Setup.
Step 2: Select the appropriate location.
Step 3: Click on Printer & Peripheral Settings > KDS Stations.
Step 4: Under the Preparation Screen tab, click on the edit button against the station you wish to modify. 
Step 5: Under the Threshold (minutes), indicate the new threshold time.
Step 6: Finally, click Submit