In order to retrieve a recently used file, you go to Start, Documents, and you will see a list of the last fifteen documents that you used. This list remains even after you turn off your computer. If you click on any of the names, the related document will appear on screen. It can be a picture, text or even a spreadsheet. This is a useful feature if you work on only a few documents.
Most people keep personal data on a diskette when they are concerned about privacy.
However, there are relatively easy ways to avoid the problems that you have described. There is an easy way to clear the Document list brought up by the start menu. This does not affect the document itself in any way. You would use this procedure only when you wanted to hide personal things. There is another method.