A preview of Windows 10 reveals something monstrous: Microsoft seems to be working to eliminate the good volume mixer of the operating system. So far, the small menu, with its white window that still reminds strongly of Windows 7, can be accessed by right clicking on the speaker icon in the tray.
Fortunately you do not have to do without the function altogether. In build 18272, only context context menu allocation has changed. Through the Windows configuration or through the "SndVol.exe" file you can still access the old volume mixer.