I replaced all the images everywhere (by this I mean in drawable folders and all Windows Assets folders and iOS Resources folder), but it still shows me the default Xamarin
I had the same problem, but the following helped resolve it:
If you get stuck on any part of this check out this short video from 02:47 onwards https://youtu.be/5g8lWPQZFxs?t=167. It helped me a lot.