How do I change my file opener to default?

[TickleMyElmo]

I downloaded a bixby remap apk from the XDA-developers site but set it to open it with malwarebytes always. Malwarebytes can't open it. How do I switch back to the default opener?

 

[habbajabba]

If something is not opening correctly I usually use mixplorer's 'open with' menu. Long press file, click the options bar in upper right corner, click openwith, then the second openwith in the popup menu bottom right corner. It just pulls up the phones open with capabilities. check the remember box first though.
https://forum.xda-developers.com/attachment.php?attachmentid=4728822&d=1553263521