Tik Tok, how to set private information only once?

Tik Tok's private messages can only be viewed once, and can only be set when sending pictures or videos of private messages.

1, open Tik Tok first, and then click me as shown in the figure below:

2. Then click Friends, as shown in the figure below:

3. Then click Send Private Message as shown in the figure below:

4. Then click+as shown in the figure below:

5, and then click on the album, as shown in the figure below:

6. Finally, choose the picture to send, and then click and watch it once. As shown in the figure below:

With the above settings, your friends can only look at the pictures once. It's ruined after reading it.