How to find and remove third-party codes from apps I've installed or reinstall

[Shinynight]

I switched from Debut theme to Debutify and everything looks fine on desktop mobile view. however when I use my phone (4.7inches) it creates huge space gap and became very messy with collection list but then I used my other phone (5.5inches) it worked exactly how it should look on the desktop mobile view, I talked with the Debutify team and they said need to reinstall any code added by third-party apps, in this case - you need to contact the APP Developer for support on this one, I've got no clue on what to do can somebody help, I don't know if this was caused by the size of the screen of the mobile device or there's certain third party codes that I need to remove.

 Iphone Mobile viewDesktop on mobile viewDesktop on mobile viewIphone Mobile viewDesktop view

[Appify_Commerce]

 I think it comes under theme development teams