Never Mind, I finally found it. Figures I would find it right after I post.
In case you want the answer it is:
Tools - Options - View - Gridline Colors (select color)

"Steve W" wrote:

Some how the default border color was changed to gray on one sheet of one
Excel file. If I choose format cells - border I can make it black, but I
would like to know how to make the default (using the border button in the
toolbar) black again.

Thanks in advance