Highlight a portion of string text (the string text is a value of a formula)

I know from several thread that this thing is possible, but there is none of the thread that i search meet my problem exactly.
so here is my problem :

Let's say i have a formula in cell A1 which have a value "The red big apple eaten by a red worm"
could anyone suggest a macro to make the text "red" in that cell become highlighted?
and if it possible i need that macro always automatically work whenever the workbook opened and for everytime I type "red", it will automatically highlighted red without I must manually run the macro.

Thanks you very much for help me

You can not format the cell partially when the contents of the cell is either formula or number.

You will need to convert the cell to the constant, so that you can do the thing.

e.g

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Hi jindon,

Thank you so much for your solution. This exactly what i want except, the code you suggest only highlight the first "red" in the text, but the second "red" in that text doesn't red highlighted.
also, can you tell me how to make the code always run in a selected range. (I want to make whenever I open the file, it will automatically run)

Try

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Marvelous jindon, you are the best!
Last question, if i want to enhance the code so it can highlight more than one type, can you make the code for me, please?
Let's say i want to make "red" and "apple" become highlighted in text "I want big red apple from the red apple tree"

Change pattern to

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Thank you again jindon!
you really solve my problem

cheers

@ RaymondH

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Thanks.

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