To modify the background picture of PPT, it is generally necessary to set the background format in PPT. Let me take Microsoft PowerPoint 20 19 as an example to show you the specific operation steps.

Step 1: Open the presentation you want to modify, right-click the background and select the Format Background option.

Step 2: Select the picture or texture fill option in the menu bar on the right side of the page.

Step 3: Click the Insert option below the image source.

Step 4: Select an option from the file in the pop-up dialog box.

Step 5: Select the picture to be replaced according to your own needs, and click the Open option in the lower right corner of the dialog box.

Step 6: You can see that the background picture of the presentation has been modified as needed.

Tip: The background of the presentation can be set as a picture, or you can use a variety of filling methods such as solid color, gradient and pattern, which can be set according to your own needs in the menu bar on the right side of the page.