Need to auto-populate cells "N/A" when selecting from a drop-down list.

Hello Forum,

I have a need to auto-populate certain cells "N/A" when I select from a drop-down list. I know about VLOOKUP and the IF formula and have used it before, But I'm not sure if it will work in my scenario. I can't enter any formula in a cell where the "N/A"s go because depending on the drop-down selected, data may need to be entered into that cell (thus overwriting that formula).
I attached a snip of the spreadsheet I'm working on.
In reference to attachment... the drop-down in column C lists numbers 1-4. For example, if 3 is selected in C27, I need an N/A to populate in cells J27, T27, P27, V27.

Is there a way make this happen? Again, I can't enter a formula into the cells that need the N/A.

I attached a spreadsheet of what I'm working on (the cells mentioned before don't match the the snip attachment, so disregard the earlier thread).

I'm unfamiliar with VBA. I'd like to learn more.

How the spreadsheet is currently filled out is how the N/A's are determined.

In reference to the attached spreadsheet...Column C has a drop down.
If selected "4", no N/A's in that row.
If selected "3", N/A in cells J,T,P,V (row 5).
If selected "2", N/A in cells H,J,N,P,R,T,V (row 7).
If selected "1", N/A in cells F,H,J,L,N,P,R,T,V (row 9).

I hope that clears up any questions.

What if you select 2 and after that you change it into 3?
What happens with 3 - G cell?

Also, there's absolutely NO REASON to use merged cells in such case.
If you wanted to have bigger cells you could just make cells bigger.

Right now, nothing happens to the cells if you change the drop-down selection. My thoughts and hopes would be if you did select a number, specific cells would fill in N/A. (I added conditional formatting to have that cell turn grey if an N/A is present).
So if my vision can work...if I were to change the number from 2 to a 3, the N/A's would change accordingly.

About the merged cells...I can't just expand a column because it would mess with my formatting on the entire page. I have a bunch of data entry forms above and below the section I posted here. And expanding would distort everything else.

If you change from 3 to 2 it will just add N/A into some cells.
But when you change 2 to 3 some N/A will be removed.
What will happen with those cells? Blank? Some formula? Some value?

please see the test file in attach.

It doesn't show you "N/A" but only uses "black out" indication in designated cells with conditional format (no formula used)

I am heading to airport to take a flight now, will come back to check .