How to change Flash Drive icons (mine shows as a default)

I always have converted .png files to .icns files. You can do this for free from iconverticons.com. Click on Use iConvert icons Online.

I think the following might work when using the .png file.

Open the .png file in Preview

Press Command+A to select the entire image

Press Command+C to copy the selection

Do a Get Info on Macintosh HD and click the thumbnail icon to select it

Press Command+V to paste the image

Right click on your Macintosh HD, choose Get Info. In the upper left corner of the Info screen there should be a thumbnail of the drive's icon. Select it by left clicking the thumbnail then press Command+X. This should restore the drive icon back to the default.

Are you dragging the .icns file over the thumbnail in Get Info of your drive? Don't use the .ico file. Put it back to the default drive icon; then try the drag of the .icns file.

If you still have the .png file, try the other way I described. I know that works because I just tried it.