Unable to find out why a cell is being overwritten by the formula in that cell.

I have 5 cells next to each other with a similar formula:

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(Course is a named cell that shows a selected variable (the name of a course))

Some of the cells show the result of the formula while others replace the formula with the result (sometimes with " ' " in front of it) seemingly at random!!

I've attached the sheet that is causing the problem Q15 to V15 is the result area. The formula in Q19 - Q24 are there because I was fed up of replacing the text result with the formula time and again.

Any advice would be appreciated.

Cheers

Hi John, this is Daminc with work profile.
The single quote was there because I was fed up typing the formula's again whenever the cell got overwritten. I don't use the single quote in the active cells.
Another possibility might have something to do with the form I am trying to build that views the data in a front end view.
I originally discounted this because, as far as I can see, all the settings are equally applied to all 5 of the cells and yet 2 of the cells repeated keeps the formula while the others change to text with a single quote in front.
If it helps, I could attach the whole workbook and you can check out the form?

Cheers Glen. I will look into that when I've sussed why my formulas are being overridden.
Currently, I'm investigating the control source with the textbox's.

There seems to be a lot of reference's to problems with the ControlSource but it seems very odd that only 3 of the 5 cells have their formulas
overridden when they virtually have the same formula and referencing