Since the creator of this thread may not know how to limit/ change the size of the logs and may want to I have posted the following as an aid in doing so.

To limit the size of the logs

Right click on the Avast orange GUI.--------- Click on “Open avast! user interface”----------Click on “Settings”--------Click on “Maintenance”----Go to LOGS and change the size and/or “Enable debug logging” if you wish.