There are 3 kinds of return types, also called newline codes: CR only, LF only and CR+LF. You file contains mixture of these types. You can distinguish these by settings the “Show CR and LF with different marks” check box in the Marks tab of configuration properties.
If you want to save the file with the same newline code, open all the files that you want to convert the newlines, and then select Save All with Encoding.
Thanks!