If you have a newer version of a file that you have already added to your site don't delete the old version! Instead replace the old file with the new version. Here's how.
Hover over Dashboard and press Files. The File Manager Menu will pop up.
Find the file you want to replace.
For more on finding files, refer to Searching files and Filtering files.
Click on the file you want to replace.
Click on the file itself, or anywhere on the row containing the file—just don’t check the box, as that does nothing.
Choose Replace in the menu that appears.
The Replace panel will appear.
In the Upload File section of the Replace panel, press the Browse/Choose File button.
As you can see in the figure, different browsers use different language here, so choose appropriately.
Select the file on your hard drive you want to use as a replacement.
Press the Open/Choose button.
Again, different browsers use different language.
Press the Upload button.
Browsers tend to use the same language here, but not always.
The Upload Complete panel indicates a successful upload.
After a few moments, depending upon the size of the file & the speed of your Internet connection, you’ll see the Upload Complete panel, indicating that the upload was successful.
Press the Continue button and you're done!
Note: all of the old links to the file are automatically updated to point to the new version of the file. You don't need to update them!