Re: change column General format yyyy/mm/dd to date mm/dd/yyyy
It sounds like XL is not currently recognizing the data as dates. Otherwise you could just change the cell's number formatting.
Select the column of cells, then go to Data - Text to Columns. Click next on the first two screens (ignoring the options selected) till you get to third screen. For "Column data format", select Date, and from the dropdown choose YMD. Click Finish, and you should be done.