Question: So I used the old `useradd` command to create a new user on Raspbian Stretch. I copied the .config directory and other dotfiles from the 'pi' user, and started using the new account. However I can't get some software to work. For instance ALSA shows 'no sound card' for my newly created user whereas it works fine with other users. Why is that so? I'm just curious. I supposed that ALSA would use the global config in /etc and hence would work just fine.

I'm aware that I should have used the `adduser` command, but being a noob I'm curious as to what are the other things that make programs work, other than the configuration files.

Answer: 
On Debian groups are very important to have access to programs. So as user **pi** I look what groups he is in by default:

```
pi@raspberrypi:~ $ groups
pi adm dialout cdrom sudo audio video plugdev games users input netdev gpio i2c spi

```

You don't show what options you have used with `useradd` to create the new LOGIN. So for reference I use:

```
pi@raspberrypi:~ $ sudo adduser myuser

```

and answered the prompted questions. Then I logged out and logged in as **myuser** and looked at the groups:

```
myuser@raspberrypi:~ $ groups
myuser

```

As you can see **myuser** is only member in group *myuser*. You should add him at least to the same groups then **pi**. Because **myuser** isn't in group *sudo* yet you have to login as user **pi** to do it:

```
pi@raspberrypi:~ $ sudo adduser myuser sudo

```

With `adduser` you can do it step by step for each needed group but with `useradd` you can do it in one step with options `--gid` and `--groups` when creating the LOGIN. Using `usermod` with that options you can also modify the existing account in one step.
As you have discovered useradd is not the easiest. It would probably be easier to delete the new user and start again.

Either way you need to set groups for the new user. The following will copy groups from user **pi**

```
sudo adduser username
#copy groups from user pi:-
    for GROUP in $(groups pi | sed 's/.*:\spi//'); do sudo adduser username $GROUP; done

```

See also <https://raspberrypi.stackexchange.com/a/83642/8697>

It is NOT a good idea to copy `.config` - you can change file ownership to new user, but there may be problems with some programs which lock profiles.