Okay…please forgive my newbiness 
…but in order to download the newest program update from 4.7 to 4.8, do I have to uninstall 4.7 first…or can I update on top of 4.7?
Thanks
Liz 
If you’re already using avast! you can simply invoke updater by right-clicking avast! icon next to the Windows clock, selecting “Updating” and “Program Update”. Thats it.
Or, if you want to keep the installed, just download the last version and run it.
It will update the existing avast installation.