The good news is, it's possible to apply a darker gel stain over the lighter fruit wood stain. The stain I like the most is Old Masters Gel Stain. It is available in several different colors and can be intermixed for custom stain colors.
It's very easy to change your fiberglass doors stain color, as long as it's a darker color.
1) Make sure the door is very clean. Wipe the door down with denatured alcohol to remove grime or oils. A good surface prepping solution can also be used, I like Paso Liquid Sander.
2) Lightly sand. Very lightly sand the door with 220 grit or a fine sanding block. This sanding will dull the gloss a little. Don't try to sand the door smooth, this will ruin it.
3) Brush on the gel stain and apply a protective clear finish. Follow the steps on this page, <a href="https://www.house-painting-info.com/staining-a-fiberglass-door.html">Staining a Fiberglass Door</a>.