To change issue thresholds and suppress issues for device groups, click the Settings icon > Issue Analysis > Issue Group Settings icon > by Device Groups and by Interface Groups side tabs. After selecting a group in the left panel, the Issue Settings for Group table lists all issues for the group and shows the current thresholds (if any) in the Criteria column, and whether any listed issue is suppressed.
For more information, Issue Group Settings and Performing Issue Suppression.