After installation Avast! hide some symbol of the programs in tasks bar. So I can not to address this programs. Why? And as this problem to correct?
1. What you are seeing is the Avast! attention icon. It is telling you that you are not fully protected. Open the Avast! GUI and go to Summary-Current Status. This will show you the problem(s) that Avast! is reporting on. See the attached example. Take note of the problem(s) and click on "Fix Now" or "Turn On". Fixing or turning on may not cure the problem until the cause is identified. Please report back with your findings.
2. That may not be what you are actually asking though. Are you also wondering why Avast's icon pushes one of your notification icons into a hidden part of the task bar? If so then right click in the task bar area then properties and tick the "show all icons and notifications" box. Or go to Control Panel and you can do the same thing there. Or you can instruct it to hide notifications that you do not care to see. Or you can click on the notification arrow and it will expand to show hidden icons. (Windows 7- may be different for other operating systems)
I think that your question is more fully answered in #2, but Avast! is also reporting that you are not fully protected so that needs to be looked into. I highly recommend that you do not hide the Avast! icon. It gives you important security information at a glance.
Off topic: GUI sure looks nice!
Below is an example only.