With the photo scanned and opened in your image editing program select all Ctrl+A and copy (Ctrl + C) and paste (Ctrl + V). This creates a new layer. Now select Hue/Saturation. In Photoshop it's Image>Adjust>Hue/Saturation and in Elements it's Enhance>Adjust colour>Hue/Saturation. The shortcut is Ctrl+U. When the dialogue box appears adjust the hue, saturation and lightness sliders until you get a suitable colour. We've gone for blue.
Now go to Layer>Add Layer Mask>Reveal All. This brings up a white square thumbnail at the side of the second layer thumbnail. The blue colour that you've set will still be seen. If you chose Hide All the square would be black and you wouldn't see any of the layer so the base layer with the original yellow would be visible.