Even if you’re seriously thinking of going that basic and proven less safe route then MSE is certainly not the choice to make.

It stopped being automatically updated, I think, in April and that has to be done manually now. MS also make finding the download page for those MSE definition updates and Windows Defender (the recommended option for Win7) suspiciously difficult too.

There are still appropriate circumstances and good reasons for using MSE but as a first choice AV it is not recommended. Defender has a very similar GUI and is said to provide better protection but quite frankly I think you’d be much better off installing an older version of AVAST (using an offline installer of course) if the current one is proving problematic for use with Win7.