Question: I forgot my password and I decided to reinstall Ubuntu with the last version. Now, how can I get rid of the old version? I use VM Virtualbox as emulator.

I must say that I am and old COBOL developer and everything is new here for me.

Answer: 
I always use `Ctrl`+`Shift`+`C` and `Ctrl`+`Shift`+`V` to copy and paste in my (non tmux) terminal.  

You can change these keyboard shortcuts in the keyboard preferences of your (non-tmux) terminal.

If however you want to keep using tmux you can also change the keyboard shortcuts of tmux by adding commands to `~/.tmux.conf`. simply add the following in that file:

```
bind-key -n [shortcut. for example Ctrl+v is C-v] [what you want to do. for example 'new-window' etc]

```

It will look like this

```
bind-key -n C-t new-window

```

You don't need the command prefix key to execute the commands in the `~/.tmux.conf` file.

For more info about the things available for `~/.tmux.conf` check [this link](http://www.hamvocke.com/blog/a-guide-to-customizing-your-tmux-conf/)

Very rudimentary copying and pasting can be done using this however for a bit more usefulness I recommend using a Vim-style copy/paste config.  

Enabling a Vim-style of copy/paste can be done with [this config file](http://jasonwryan.com/blog/2011/06/07/copy-and-paste-in-tmux/) or [another config file](https://gist.github.com/justin808/9493723). These do however require the use of the prefix key.  

Someone even made a [tmux extension](https://github.com/tmux-plugins/tmux-yank) to simplify the copy/paste action to the system clipboard in tmux. It might be worth a look.

If you want an alternative for Tmux you might try dvtm (`sudo apt-get install dvtm dtach`). I haven't used it myself but it looks like it has similar options.
To copy, use `Ctrl`+`Shift`+`C`

To paste, use `Ctrl`+`Shift`+`V` or `Shift`+`insert`

Another way to do this:

First run command `screen`, after then can do following steps:

* Press `Ctrl`+`a`+`Esc` It will put the screen in copy mode.
* Now, move the cursor to the beginning of the section to copy & hit enter.
* then, move the cursor to the end of the section to copy & hit enter.
* Now, press `Ctrl`+`a`+`]` to paste.