It seems impossible to apply reverse effect to selected part of the track without affecting all the tracks in project.
All the other effects work fine and can be applied separately, without changing non-selected tracks.
Am I doing something wrong or it is a bug 
Regards
I think you’ve found a bug 
Testing on the released 2.1.3 version and the latest unreleased 2.2.0 Beta shows that
a) If you have Sync-locked tracks on - then yes, the reverse is applied to all the sync-locked tracks
b) with Sync-locked tracks turned off then this does not happen, only the selected track (or tracks) have the reverse appliued to them.
I really don’t think that a) should happen so I will be logging this as a bug on our Bugzilla reporting system - thanks for finding, and reporting, this.
What you need to do is to turn sync-lock off. In 2.1.3 there is a clock icon in the Edit Toolbar, ensure this is in the up position.
http://manual.audacityteam.org/man/edit_toolbar.html
You can turn it off fbt re-clicking the bitton - or use the Tracks menu: http://manual.audacityteam.org/man/tracks_menu.html
The other visual cue is that with multiple tracks and sync-lock turned on then you should see little clock icons in the botton right of the Track Control Panel at the left of each track’s waveform. See: http://manual.audacityteam.org/man/sync_locked_track_groups.html
Because we realized that too many folk were accidentally turning sync-lock on by inadbertently nudging that button for the upcoming 2.2.0 we have removed that button from the Edit Toolbar and the sync=lock can only be activated/deactivated via the Tracks menu.
WC
I’ve just logged this: http://bugzilla.audacityteam.org/show_bug.cgi?id=1751
We are so close to Realease Candidates for the upcoming 2.2.0 so it is unlikely yo be fixed for that release - but there is a good chance to get it fixed for future releases.
Once again, thanks for spotting that maxi1
WC
Thanks, I’d never guess what’s that icon of the clock used for. When it’s off everything works fine 
maxi1,
some discussion among the developers and QA folk (small in number) has resulted in a consensus that the behaviour that we have where all audio (and labels) in a sync-locked track group are reversed (as you discovered) is both required and desirable behaviour with reverse in Sync-Locked Track Groups.
Accordingly I updated the (alpha 2.2.0) Manual today:
https://alphamanual.audacityteam.org/man/Reverse
and
https://alphamanual.audacityteam.org/man/Sync-Locked_Track_Groups_-_Editing#Reversing_audio
Glad you now know how to turn sync-locking off and you now have it working as you want
And BTW many thanks for stumbling into this and pointing it out - I never knew it did that, most useful to know 
Thanks,
WC