How can I change the default application that archive manager uses?

When I had installed the rar application the archive manager was using that one which had problems with non-english characters. I uninstalled it and the archive manager used p7zip. The question is how can I make the archive manage (and extract here) to use the p7zip instead of rar but have both installed at the same time.

You'll need to associate p7zip with .rar file types. To do so find a .rar file and Right Click that file and choose "Open With Other Application..."

In the "Other Application" menu select "Use a custom command" and enter /usr/bin/p7zip -d and check the "Remember this application" checkbox.

Personally I found that the best archive manager which support non-English characters is PeaZip PeaZip web site. It has a support for RAR archives and is able to do many other operations.

In order to make this (or other) archive manager as a default choice: from file (archive) Properties menu select a Default application (for current file type).