Here is the complete content for the `How to use.txt` file, starting from **point 3** and including all the missing information:

```plaintext
### How to Install, Start, and Use the Signage Player Application

This guide provides step-by-step instructions for installing, starting, and using the signage player application.

---

## 3. Using the Application

### MediaPlayer Screen
- **Play/Pause Button**:
  - Toggles between playing and pausing the media.
  - Automatically resumes playback after 30 seconds if not toggled again.
- **Next/Previous Buttons**:
  - Navigate to the next or previous media in the playlist.
- **Exit App Button**:
  - Opens a password-protected popup. Enter the `quickconnect_key` from the configuration file to exit the app.

### Settings Screen
- **Configuration Fields**:
  - Update fields like `screen_orientation`, `screen_name`, `quickconnect_key`, `server_ip`, and `port`.
- **Save Button**:
  - Saves the updated configuration and returns to the MediaPlayer screen.
- **Exit App Button**:
  - Opens a password-protected popup. Enter the `quickconnect_key` to exit the app.

---

## 4. Configuration

### Configuration File
The configuration file is located at:
```bash
app_config.txt
```

### Example Configuration
```json
{
    "screen_orientation": "Landscape",
    "screen_name": "MyScreen",
    "quickconnect_key": "12345",
    "server_ip": "192.168.1.1",
    "port": "8080"
}
```

### Updating Configuration
1. Navigate to the **Settings Screen** in the app.
2. Update the fields and click **Save**.
3. The configuration will be saved to `app_config.txt`.

---

## 5. Troubleshooting

### Permission Denied for `run_app.sh`
- Ensure the script is executable:
  ```bash
  chmod +x /home/pi/Desktop/signage-player/run_app.sh
  ```

### Application Does Not Start on Boot
- Verify the `~/.bashrc` or `crontab` entry is correct.
- Check the script's permissions and paths.

### Media Files Not Playing
- Ensure media files are downloaded to the correct directory:
  ```bash
  /home/pi/Desktop/signage-player/src/static/resurse
  ```
- Check the playlist configuration and server connection.

### Password for Exit App
- The password is the `quickconnect_key` from the configuration file (`app_config.txt`).

---

Let me know if you need further clarification or additional details!
```