Customizer 10000 cannot change the stitch count of your embroidery once it has been created. You can resize your embroidery up to 20% smaller or larger, but it will not alter the stitch count. It will make the stitches closer together or further apart, depending on how you sized the design.
It is better to change the size of the graphic image to the size of the embroidery you ultimately want to create, rather than resize the finished embroidery.
When you open a graphic in Customizer 10000 EasyImport, it will be sized to the size of the hoop selected. It will also have sizing points surrounding the graphic.
You can slide your mouse arrow over the sizing points to change them to a double arrow. When they change to a double arrow, you can move them to change the size of the graphic.
If you select one of the four corner points, you can change the size of the graphic proportionately. In other words, height and width will change at the same rate, so your picture will remain with the same proportions, only smaller.
If you select one of the four side points, you can change the length or width of your graphic. For example, if you select the point on the right side and slide it toward the center of the graphic, when you release the mouse button your picture will appear taller and thinner.