Exclude from analysis on closed survey: Will changing setting invalidate my data?

Hi there. I have a several matrix questions in my survey with 1-5 scale questions plus a "N/A / did not use" option, which I added to the auto-scale Qualtrics verbiage. In analyzing my data, I see that I should have selected "exclude from analysis" for the "N/A" options, since otherwise these are included in the median calculations.
I see that I can revise the field to "exclude from analysis" (red in my native survey design, but I'm concerned that it will invalidate my data when I click publish. Can someone confirm for me if it's okay to make this change on a completed survey? Or did I need to do this at the design stage (and can't change now). I'm worried to click Publish...