Mac files all have dates associated with them, especially the last date they were opened or modified. The date will show up next to your files if you display them in list form. If you want to change the date associated with the file you can do so with the Terminal. The Terminal is a utility program for Mac computers that allows users to input command lines and control the computer with them.
Open the "Go" menu and select "Utilities." Click on "Terminal."
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Type the following into the Terminal window: "touch -mt YYYYMMDDhhmm." YYYY is the year, as in 2001. MM is the month, like 03. DD is the day as in 06. Hh is the hour as in 08. Mm is the minute as in 34.
Select the file whose date you want to change and drag it over the Terminal window. Drop the file into the Terminal. The file's file path will show up in the Terminal window.
Click "Return" on the keyboard.