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.
Inspired by the answer Pilot6 gave, I fixed mine by opening `/home/dell/.config/pulse/default.pa` in Gedit and doing a search for volume. It found it in 2 places and changing the second one that it found to the following set my startup volume to 63%.

Previous entry:

```
set-sink-volume alsa_output.pci-0000_00_1b.0.analog-stereo 65536

```

New entry:

```
set-sink-volume alsa_output.pci-0000_00_1b.0.analog-stereo 41288

```

Super-user privileges were not necessary, I just made the one simple change and restarted the machine and it worked fine. Just divide the 65536 by whatever percentage you want to set it to if you don't want 63%.

Hope this helps.