get a picture that you want to display as the default logon picture. The image can be in .JPEG, .BMP, .DIB, .RLE, or .PNG format. The image size should be 125x125px, in order to display properly.

The default icon storage location in Windows 10 ... Click on 'Change Icon' from the 'Customization' tab. Then, various icon images will be displayed so that you can change the icon.