Ошибка при установке Steam

ОС - Ubuntu Mate 16.04 Я думаю, что я изменил некоторые пути к репозиторию при установке моего последнего программного обеспечения. Что я должен сделать, чтобы сбросить их?

При установке через Терминал:

user@user:~$ sudo apt-get install steam
[sudo] password for user: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libqt5opengl5 libqt5printsupport5 linux-headers-4.4.0-31 linux-headers-4.4.0-31-generic linux-image-4.4.0-31-generic linux-image-extra-4.4.0-31-generic
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  steam:i386
0 upgraded, 1 newly installed, 0 to remove and 1 not upgraded.
Need to get 0 B/874 kB of archives.
After this operation, 2,662 kB of additional disk space will be used.
Preconfiguring packages ...
Selecting previously unselected package steam:i386.
(Reading database ... 269250 files and directories currently installed.)
Preparing to unpack .../steam_1%3a1.0.0.48-1ubuntu3_i386.deb ...
dpkg: error processing archive /var/cache/apt/archives/steam_1%3a1.0.0.48-1ubuntu3_i386.deb (--unpack):
 subprocess new pre-installation script returned error exit status 30
Installation terminated: Steam License Agreement was DECLINED.
Errors were encountered while processing:
 /var/cache/apt/archives/steam_1%3a1.0.0.48-1ubuntu3_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

При установке через Software Boutique

Появится следующая подсказка

Не удалось загрузить информацию о хранилище

details: W:The repository 'http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu xenial Release' does not have a Release file.
W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
W:See apt-secure(8) manpage for repository creation and user configuration details.
E:Failed to fetch http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not Found,
E:Some index files failed to download. They have been ignored, or old ones used instead.