avira-avast-windows defender

i have happily used avast free anti-virus as my primary tool, together with malwarebytes as secondary security layer.
recently, I read avira is a better anti-virus engine than avast, but it's features weren't quite as pro-active- more reactive (I don't know if this is true or not, or how to phrase it better technically).
but for this reason, of this understanding, I downloaded avira free anti-virus which I intended to use as secondary security layer- ie. run manually maybe once a week to confirm the real-time avast protection.
however, avira seems to turn itself on every reboot, which is not desirable (I understand that running both real-time may unnecessarily slow-down the computer performance, etc.).
how can I turn-off avira until needed?

secondly, once I installed avira, my windows defender now says it's turned-off...any relation?

thank you