Piano -

The way I'm reading your post I'm guessing you are trying to edit and save a .csv file. Is that the case?

Even though Excel has the .csv file type associated to it in order to directly open it - it isn't a true Excel file. Any edits you make as far as formatting are lost unless you save it as an Excel file ( .xlsx ).

.csv files are really meant to make files compatible with multiple programs that otherwise wouldn't be able to exchange data.