For several years I have used the "Shadow" feature (standard on the PPT
toolbar) with my text to make it show up better on my backgrounds. Normally,
the shadow color depends on the color of the background (i.e., with a black
background, text is automatically given a white shadow; white background -
text is automatically given a black shadow) which is changeable through the
"Shadow Color" tool. Lately, the shadow color appears as grey and is not
changeable. How can I correct this issue so that my shadow returns to
"normal" and changeable?