Find and Replace Formulas

WendyVN  maybe there is another way but this might work for you if they are all in the same column:

1) convert worksheet to R1C1 style

2) find & replace

3) convert workshet back to A1 style

so step 1 is go into excel options select formulas section and click the checkbox for R1C1 style.  See image below

now all the formulas will look something like =RC[-5]+RC[-4]-RC[-3]

highlight that formula and go into find and replace and paste that into the find

under replace you can change the + to - so it will be =RC[-5]-RC[-4]-RC[-3]

then go back into options and unclick the R1C1 checkbox.

For the future consider using array formulas so =A1:A100 + B1:B100 - C1:C100 which will do the calculation on all 100 rows and then if you need to change you only change the 1 cell.

Or better yet you can use LAMBDA so you define a LAMBDA function like MyCalc

MyCalc := LAMBDA(a,b,c, a+b-c)

then you have =MyCalc(A1, B1, C1) or =MyCalc(A1:A100, B1:B100, C1:C100) in the formula boxes.  Then if you need to change the calculation you go back into your Name Manager and change the definition of MyCalc to be MyCalc := LAMBDA(a,b,c, a-b-c) and then all cases of that are corrected.