Can I protect my Powerpoint presentation with a password?

I fully agree with MR Asim Ali  

In an open presentation, click File > Info > Protect Presentation.

OR 

Microsoft Office Button -> Prepare->Encrypt Document.

In the Encrypt Document dialog box, in the Password box, type a password, and then click OK.You can type up to255 characters. By default, this feature uses AES128-bit advanced encryption. Encryption is a standard method used to help make your file more secure.

here's the solution

To encrypt your presentation and set a password to open it:

1. Click the Microsoft Office Button , point to Prepare, and then click Encrypt Document.

   

2. In the Password box, type a password, and then click OK.

   You can type up to255 characters. By default, this feature uses AES128-bit advanced encryption. Encryption is a standard method used to help make your file more secure.

3. In the Reenter password box, type the password again, and then click OK.
4. To save the password, save the file.

while encryption is another type, you need to sign up for the Microsoft live account as that feature can not be enabled without credentials of the user.

1. Click the Office Button in the top left corner of the screen
2. Choose Save As.
3. In the bottom left corner of the Save As dialog box, click on the Tools button.
4. Choose General Options ....

There are two password options available for you to add to your presentation.

Password to Open

• This is a security feature that will encrypt your presentation and allow you to control who has access to the file.

You can just keep both ppt files open and you can select the slides you want to copy from the left pane where slides are listed, and you can go the another ppt file come to the slide where you want to insert the slide and paste you will get it done.

set a password for change