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: 
I created a new user and found that sound works correctly with the new user. That means that something was wrong in user configs. I found some configs and it looks like the problem is solved. The files were not in text format and I have no idea what that format is.

I removed all files from `~/.config/pulse/` and rebooted. Now it works OK.

I also removed all files from `/root/.config/pulse/` to fix 100% volume on login screen.

I think they've changed format of some config files in the new version of `pulseaudio`. The config from 14.04 confused `pulseaudio` in some way.

I saw some bug reports about this issue. It may happen when you replace Ubuntu versions with the same `/home`. 

**Update:** This looks like a distro upgrading bug. I upgraded 14.04 to 16.04 on another computer, and there was the same issue.

`cookie` file needs to be removed in `~/.config/pulse/` after an upgrade.
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.