@MahaB82A
Check your file associations. Windows looks at the extension and associates it with an application. If/when it needs to be changed, you do it through Windows OS. Here are directions from Microsoft support:
https://support.microsoft.com/en-us/windows/change-default-programs-in-windows-e5d82cad-17d1-c53b-35...
You will need to select a different application to open your PNGs, such as Windows Photos, Photoshop, or another image editor you have installed.
Jane