https://support.torproject.org/tbb/tbb-2/
And I have already managed to change the "Entry guard" several times: from United Kingdom to Germany and to Ukraine, to France.
But the lamers can not do it and do not even know about the new feature of The Tor Project
I continue the experiments...
I revealed that Tor begins to ignore directive ExcludeExitNodes in torrc file.
Moreover, the application when starting, removes this directive the configuration file.
I solved this problem. Simply and reliably