I keep getting notices that I need to update, but when I try I get the message that everything is already up to date. Why is this, and is there some way to get only when I really need to update?
Update Avast or the virus database or, one of the programs on your computer ???
A screenshot of the notice would be helpful. 
I have tried to update and it says it’s up to date. I don’t understand what you mean about updating a program. Haven’t been able to get a shot yet.
If you have the Software Updater installed (installed by default) you would also receive a notice if a monitored program is not up to date.
Finally got a screen shot - attached. Nothing about a program needing up date. At least trying to attach screen shots.
Perform a repair of avast and try to update again.
How does one repair Avast?
Go to control panel, programs and features, right click on Avast, change, then repair. Reboot after repair is finished.
Thanks, midnight. Will let you know what happens.
Got the notice to update and the same thing happened - it is up to date.
Perform a clean installation of the latest avast version.
Eddy, thanks - have done as you suggested. Will let you know what happens if anything untoward.
Ok, keep us informed.
Everything appears in good order now. Thanks every one for your help.