This kind of this is always a pain in Excel, you have to convert the values using a function because once Excel converts the cells to Time they are stored internally as numbers. Here is the best way I know how to do it:
I’ll assume that your times are in column A starting at row 1. In cell B1 enter this formula: =TEXT(A1,"hh:mm:ss AM/PM") , drag the formula down column B to the end of your data in column A. Select the values from column B, copy, go to column C and select “Paste Special”, then select “Values”. Select the cells you just copied into column C and format the cells as “Text”.