I will preface this with I am brand new to Excel Power Query, just learned about it last night and made my source folder containing the csv files to merge (5 total – 2020, 2021, 2022, 2023,2024 (Current year data)). I got them successfully merged and into the output table in excel. All of the data is there.

The problem I am running into is I am working with data from well before my time and a lot of it isn’t in the best shape (missing fields, different items in the fields from older procedures, etc.).

So I’ve gotten the files merged and went into the output table and started correcting some of these issues. When I went back into the query editor, all of those changes reverted back to the original. Am i missing an easy step like a refresh or do I have to go back into all of those source documents and correct them there prior to merging?

Pardon my ignorance.