Avast compatibility mode

How do you install in this mode?

avast doesn’t have a compatibility mode.
What exactly is it you mean ?

Gator71 if you mean by the system requirements for Avast. Please read the following link https://www.avast.com/faq.php?article=AVKB44

Avast works on both 32 and 64 bit systems and comparability mode isn’t required to run Avast.

I saw it on a forum…

From what the thread says, Avast can run alongside another AV in compatibility mode???

http://malwaretips.com/threads/list-of-companion-antiviruses.12521/

https://blog.kaspersky.com/multiple-antivirus-programs-bad-idea/