Hello,
On top of the advice by Akash, here's the official documentation for this: https://docs.microsoft.com/en-us/powerapps/maker/model-driven-apps/change-custom-entity-icons
You need to make sure that you are customizing the "Unified Interface" icons, which are not the same as the web client icons.
The Unified Interface is the perfect opportunity to refresh your app icons.
I advise that instead of PNG you always prefer SVG format that renders better, regardless of the screen resolution.
There are a lot of free libraries of icons (e.g. Syncfusion: Metro Studio, which is my favorite to do it in bulk and has advanced formatting options).
Example of SVG icon format that renders well in the Unified Interface:
- Width​ and height: 16px​
- Padding : 0px
- Background: transparent,
- Icon color: #FF000000
To avoid rendering issues in older browsers, open the SVG file with an editor (e.g. Notepad) and remove fill="#000000"
Henry
