Unity: How can I make Alt+TAB browse through all my windows without grouping them?

Here is my solution:

1. Install compizconfig-settings-manager and open it (type ccsm in terminal).

2. Go to Desktop > Ubuntu Unity Plugin.

3. Open Switcher tab and make key to start the switcher and key to start the switcher in reverse disabled.

4. Go back to CompizConfig Settings Manager.

5. Go to Window Management and enable Application Switcher.

6. Open Application Switcher and change key bindings of "Next Window (All windows)" to Alt-Tab and "Prev window (All windows)" to Shift-Alt-Tab.

Then you will start to use a different switcher instead of Unity's switcher.

The other option -which I'm testing out this week- is to have the ALT+TAB switch between apps, and ALT+| switch between windows of the same app. It sounds complicated but it works surprisingly well.

Use case A: You're on Firefox and want to switch to Thunderbird: ALT+TAB.

Use case B: You're on a Calc window and want to switch to another Calc window: ALT+|.

In B, you could use the old way of ALT+TAB, where it cycles through all your windows, but it can take a while to do that if you have more than a few windows open. With this thing, you always know where you want to go, and choose the quicker way to get there.

I choose | because it's just above TAB, so my brain and my finger don't need to move very far.

To enable this: System Settings > Keyboard > Shortcuts > Navigation > Switch windows of an application (it's just underneath Switch applications, which is how I found it).

Easy to test, safe, easy to revert, no need to install anything.

Just thought I would share this since I tried to follow the accepted answer but couldn't find the Ubuntu Unity switcher. I'm running 18.04 and I was able to change the alt-tab behavior by:

1. going to settings->devices->keyboard
2. scroll down to the shortcut for "Switch Windows" (under the "Navigation" section)
3. change the shortcut for Switch Windows to alt-tab

This will overwrite the shortcut for "Switch Applications" which is the default behavior for alt-tab