The first step once confirmed that the correct drivers and by the way sound app is installed is to set to the speaker settings for 5.1 or 4 speakers depending on preference. You may want to check on the Windows sound mixer settings as well since many often forget about that other mixer being there.
The first test once the settings are looked over is going into the Control Panel>Sound section there to run the test/configuration wizard which will verify each pair of speakers first front then back as you go along. That is found in the Playback tab when first clicking on the CP>Sound and seeing the popup window appear.
(refer to attached images for both Windwos sound mixer, Sound configuration wizard)
As you will see from the second image there for the configuration wizard I use a separate expansion card(preferred here) while you would still look through that wizard. With the Creative Audio Console/Volume Panel you generally expect a move evolved mixer.volume control panel while most onboard sound setups also provide some smaller form of mixer app you would need to look at as well.
Another trip up found with some 5.1 speaker sets is on the center speaker or other volume and balance controls where sometimes tweaking them is required when it seems sound will drop off from the rear speakers. If the bass is up a bit the quality of sound from the rear pair despite having a woofer below can suffer! Then you have to tweak the tremble if these controls are present to clean up the sound from the rear.
As for 3rd party audio mixers you can find a ton of those. Power Mixer however replaces the standard volume control/mixer included in Windows. Volume control for Windows - Power Mixer