Changing color theme

Hello,

I need to change the colors on a ton of graphs quickly. Currently they are set based on our color theme. I tried making a new color theme and applying it, but I get the error:

<filename>intang:
You cannot use this command on a protected sheet. To use this command you must first unprotect the sheet (Review tab, Changes group, Unprotect Sheet button). You may be prompted for a password.

But... the sheet is not protected! I tried protecting it and then unprotecting it, as well as selecting all the cells and unclicking "Locked" under "format cells", but nothing has worked.

The file is an Excel 2007 macro-enabled workbook, and the color theme is listed under "built-in". Maybe I could modify the built-in color theme itself? How do I do that?

I'm not using code - it's not my worksheet, I just do the layout for when we print reports, so I'm in charge of colors.

I was clicking on "Page Layout" -> "Colors" -> "Custom 1"

The problem here is that if ANY sheets are protected, you cannot change the color scheme. So you might find there is another sheet in the workbook (which may be hidden) that is protected. Unprotect all sheets, and you are good to go.