You can press the button Encrypt to make a new encrypted version of the file.
Or open the decrypted window and press the button Decrypt to decrypt the originally encrypted file to the unencrypted one.
If you make a new encrypted copy of the file, you can drag and drop the encrypted document onto the drop box to the right. If you want to put it back to the original state, drag and drop the unencrypted document onto the encrypted document.
You can drag and drop files over each other during encry