|re: "all cells in a workbook"|
All cells in a workbook or all cells in a worksheet?
In addition, I assume you mean that you want to change all cells that contain <title="text string"> such that the text string turns red.
Can you narrow the range down a liilt bit?
e.g. Are these cells all in a specific column or row or randomly spread out through a worksheet?
Are they all on one sheet or does the change have to made to multiple sheets?
The more detail you provide, the more specific a solution we can offer.
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