Question: This is a bit mysterious problem.

I upgraded Ubuntu 14.04 to 16.04. Now after each reboot the sound volume resets to 100%.

It is mysterious because it happens only on one computer, on another the sound volume is saved OK.

The other mystery is that I have Ubuntu 14.04 and 16.04 on the same computer with the common `/home`. On Ubuntu 14.04 the sound is aved OK, but on 16.04 it does not.

What can I do to troubleshoot this issue?

Answer: 
Disable the "Keep Settings" in the PulseAudio Equalizer.
So, for this problem-- the accepted solution is to mess with the pulse audio configs.

I was here in a desperate attempt to fix something in Raspbian.

A hack that would work for both is putting the amixer solution from @proprocrastinator in your ~/.profile configuration.

That way whenever you log in, ~/.profile runs, and

```
amixer -D pulse sset Master 50%

```

is executed as a result.

I had a problem with my microphone, fixed similarly with

```
amixer sset MIC 100%

```

for anyone else wandering in from the google for the same thing.

...I don't think this is the optimal solution. But, it probably will work if you can't find a better way to do it.