Your mash volumes are controlled in your mash profile. Is there a pattern to when you have too much water in the initial infusion? Like higher grain bills?
You can set the volume of your mash tun in your equipment profile to be the level of your overflow pipe. Then when the volume exceeds the capacity, the 'total mash volume needed' on the mash tab will turn red and you can see it and make an adjustment before you brew.
To adjust the mash volumes, you can open up the mash profile and edit the infusion step to add less water when adding the grain (infusion step).