MS picture format Question

 I often use MS Excel for creative uses but I was baffled when it didn't cooperate with me recently.

  Usually I can take a black and white image and change the line color 

 however I wanted to change the color to purple instead of blue  and when I choose more variations and selected purple it colored the background (not the lines)

 so then I used the transparency option to get rid of the white background  and this is what happened when I chose the color purple

 instead of the lines turning purple, it created a splatter effect. Does anyone know if there's a way to add to (or change)  the "recolor" options or are the colors shown in the drop down menu the only options that are pre-set and can't be altered? I ck'd picture color options and was still unable to get the solid purple lines of my image. Thanks in advance