how do I keep computer from turning off after scan?

My avast was set at the computer shop to automatically turn off computer after scan. I have looked on every link and can’t find where to change this setting so the computer will stay on.

https://www.avast.com/faq.php?article=AVKB177

You need to open the settings for the scheduled scan that you are running.

AvastUI > Scan (icon) > Scan for viruses - from the next screen, from the drop down menu select the scan.

Now click the Scan Settings at the bottom of that screen > Scheduling > Uncheck the Shut down the system after the scan finishes.