Need vba to copy a set of columns and paste them back.

I have columns B, D , E , X etc (more than one usually)

I need a trigger to copy their contents and paste it on top of them (yes you understood correctly you copy B column and paste it back into B column). By a method that excel detects so it triggers its automatic re-calculation of depending cells function.
The triggering of this can be whatever is convenient for you. I can dedicate a cell that says "on"/"off". I don't need it to loop - Just once upon entry/switch.

I need this because I use another vba function that does not detect changes on the content it references.

in case you want to tackle the source:

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Its used like this
=StrOffset("namedrange 3 namedrange 1 namedrange 5",1)

Bernie Deitrick suggested i put it inside a regular function like =IF(ISBLANK($TT$1),StrOffset("namedrange 3 namedrange 1 namedrange 5",1),"re-check")
Which normally does the trick but crashes when the cell containing the above mentioned formula is referenced from another file via link cell (you copy this cell and "paste link" it in another excel file). Although it only crashed when you press "UPDATE" at the "This workbook contains links to external sources.... do you want to update, not update or get help" prompt. Otherwise it works normally.

I've provided both so you can pick your preferred approach.