Play music across multiple slides in your slide show
You can add a song to a presentation and play it across slides in the background of your slide show. If you want to use music from the web, you have to download it to your computer before you can use it in a presentation. On the Insert tab, select Audio, and then Audio on My PC.
Add and record audio in PowerPoint - Microsoft Support
Play music for the duration of your slide show. Training: Add and record audio, such as music, narration, or sound bites, to your PowerPoint presentation and select the playback options. Watch this video to learn how.
Create professional slide layouts with Designer - Microsoft Support
Designer improves slides for Microsoft 365 subscribers by automatically generating design ideas to choose from. While you're putting content on a slide, Designer works in the background to match that content to professionally designed layouts. Designer is …