I need a new avatar/sig, and I'm having trouble resizing the picture.

The avatar is 150 x 154.
On Paint, I went under 'Image' and clicked 'Attributes'.
I put the units in 'pixels' and changed the width/height to 130 x 130.
Though that didn't resize the picture, it just cut some off until it was the correct size.

What am I doing wrong? How can I resize my images without distorting the picture quality?