[Campaign override option - setting exact number of impressions/ decreasing the time between banner cache update]

Hi,

I currently use Revive Adserver 3.2.1. I need to use the "campaign override option" with limit to add impressions. 

Revive Adserver 3.2.1 currently refreshes in 20 minutes and i get a vast amount of additional advertising impressions for this time period, since I have significant traffic on my website. How can I set the refresh on less than 20 minutes, maybe 1 or 30 seconds, so I can at least limit the extra impressions as much as I can. I tried to decrease the refresh time in configurations->banner delivery settings-> Time Between Banner Cache Updates (seconds), but it did not work. Once I set it to less than 20 minutes, it goes back to 20.

 

How can I set exact limit of "override" impressions, without showing extra impressions? I need the add to dissapear after exact number of impressions, not more. 

 

Just a note, we use memcache for Banner delivery cache store type

Thanks for your help!