Did you change the file folder settings in Endnote (edit>preferences>folder locations)? They cannot point to the program folder styles location on the C: drive which is where the default list of styles is located (which is write protected by Windows’ operating system), and must point to an existing folder elsewhere that has write access - (for example mine contains the following after my network home drive info … \lmw\My Documents\EndNote\Styles). This way, the original style is retained in the write protected location, and you generate the modified copy in the User location which is not overwritten when the program itself is updated. Do not use the same name, as Endnote then has two copies, and usually defaults to the write protected location version.