How do I update the software

The answer to this depends mostly on if your soundbar model. Some Polk MagniFi series soundbars receive their updates from smart home apps like Google Home - pairing it to Google Home and setting up WiFi/Ethernet connectivity allows the firmware to auto-update.

By any chance are you trying to fix a specific issue with the soundbar? If so, ensuring the soundbar has its latest firmware is a good initial step. There may be more specific solutions to other issues though.

If you could provide us the model number of the soundbar it would be helpful for us to be able assist you further.