How to Change a File Date
Changing the file date may prove necessary when you need a specific time or date for a file. Files with incorrect dates can make it harder to search for the file you need by preventing the ability to search for files by the creation or modified date. Luckily, Windows and Mac operating systems provide ways for you to change the date that you last modified or created a file. If you need to change the file creation date, you must use a workaround to change the date on your computer and then save the file as new.
If you only want to change the file date so that it reflects the current time, you can open the file and use the Save command to change the modified date to the current system time. This won't work properly if you don't have your system clock set to the correct date and time. Also, this process doesn't allow you to change the original creation date. However, it does make it possible to search for recently modified files using File Explorer in Windows 8.1.
Change File Properties
When you want to change the modified date of a file, you can change the date in the file properties dialog. This won't work for certain types of files, including text and rich-text formatted files. Double-click the folder with the file you want to change and click on the file name. In the details pane, click on the value that you want to change. If you can't select the value, then you can't edit it. You can also right-click the file, select "Properties" and choose the "Details" tab to access additional values not present in the details pane.
Change System Date
When you need to change the creation date of a file, you can change the date on the system clock and then save the document or media file as a new file. This takes the date from the system clock and sets it as the new creation date. Right-click the current time and select the option to "Adjust Date/Time." Choose the option to "Change Date and Time..." and input the new information in the time and date fields. Press "OK" to save your changes and then open the file you want to change. Select the "File" menu and choose "Save As." Type a new name for the file and save the file. If you select the Save option instead of Save As, then the file only updates the modified date and not the created date.
Change the Date on a Mac
On a Mac you can access the file properties and make changes to the file data using the same basic methods that work on Windows systems. Change the created date by clicking on the system clock, selecting "Open Date & Time Preferences" and inputting new data in the time and date fields. Make sure to uncheck the option to "Set Date and Time Automatically." Once you change the clock, open the file and select the "File" menu. Press the "Option" key and select "Save As..." from the drop-down menu. Use a new file name and save the file. If you only want to change the modified date, set the system time to the appropriate time and use the "Save" option from the File menu.