2 things you can try:
1) You can upgrade to a newer version with LO ppa
2) You could rename your LO directory profile (see https://wiki.documentfoundation.org/UserProfile#GNU.2FLinux) and test again

(In reply to Julien Nabet from comment #1)
> 2 things you can try:
> 1) You can upgrade to a newer version with LO ppa
> 2) You could rename your LO directory profile (see
> https://wiki.documentfoundation.org/UserProfile#GNU.2FLinux) and test again

1) I rather let Ubuntu manage the versions and so keep me up to date. I'm using:
Version: 5.3.1.2
Build ID: 1:5.3.1-0ubuntu2

2) I did this and the ctrl+shift_arrow (selecting whole words) works now. Copy paste (ctrl+c/v) still doesn't.

(In reply to eyallior from comment #2)
> ...
> 1) I rather let Ubuntu manage the versions and so keep me up to date. I'm
>...
Last stable LO version is 5.3.5. I don't know which Ubuntu version you use but this bug may be already be fixed on LO side.
So at least, give a try with LO from ppa then revert to previous version if you just want to let Ubuntu manage version.

Lior: since it concerns Hebrew, thought you might be interested in this one.

(In reply to Julien Nabet from comment #3)
> (In reply to eyallior from comment #2)
> > ...
> > 1) I rather let Ubuntu manage the versions and so keep me up to date. I'm
> >...
> Last stable LO version is 5.3.5. I don't know which Ubuntu version you use
> but this bug may be already be fixed on LO side.
> So at least, give a try with LO from ppa then revert to previous version if
> you just want to let Ubuntu manage version.

Version: 5.4.0.3 and still can't copy paste with hotkey (ctrl+c/v) in Hebrew

Thank you for your feedback Eyallior.
Since I don't have more questions, i put the status back to UNCONFIRMED.

Thanks Eyal for the report.

I couldn't reproduce both problems on Debian testing.
Version: 5.4.0.3
Build ID: 1:5.4.0-1

From my memory, the copy/paste issue is mostly dependent on your x-window and graphical environment. What environment are you using? (please also mention Ubuntu version).

For me, it works fine on Debian testing with Mate (GNOME 2 fork).

(In reply to Lior Kaplan from comment #7)
> Thanks Eyal for the report.
> 
> I couldn't reproduce both problems on Debian testing.
> Version: 5.4.0.3
> Build ID: 1:5.4.0-1
> 
> From my memory, the copy/paste issue is mostly dependent on your x-window
> and graphical environment. What environment are you using? (please also
> mention Ubuntu version).
> 
> For me, it works fine on Debian testing with Mate (GNOME 2 fork).

Ubuntu 17.04
Unity

(In reply to eyallior from comment #8)
> (In reply to Lior Kaplan from comment #7)
> > Thanks Eyal for the report.
> > 
> > I couldn't reproduce both problems on Debian testing.
> > Version: 5.4.0.3
> > Build ID: 1:5.4.0-1
> > 
> > From my memory, the copy/paste issue is mostly dependent on your x-window
> > and graphical environment. What environment are you using? (please also
> > mention Ubuntu version).
> > 
> > For me, it works fine on Debian testing with Mate (GNOME 2 fork).
> 
> Ubuntu 17.04
> Unity

I reproduced the issue:

OS: Ubuntu 17.04 (Fresh install on VM)
DE: Untiy
Libreoffice: 5.3.1.2 (Build 1:5.3.1-0ubuntu2)
Locale: he-IL (en_IL)

Results:
1. CTRL+SHIFT+ARROW allows selecting whole words, but not before changing RTL / LTR direction depending on the SHIFT selected, and this happens both in hebrew and english 
2. CTRL+C/X/V doesn't work with hebrew keyboard

Results are the same after a full upgrade

NEW per comment 9.

Eyal: it worked in an older version?

(In reply to Buovjaga from comment #10)
> NEW per comment 9.
> 
> Eyal: it worked in an older version?

It works in 5.1.6.2 on an older laptop running ubuntu 16.04

Ok, you guys who can repro could try bibisecting: https://wiki.documentfoundation.org/QA/Bibisect/Linux

I guess using this repository: https://gerrit.libreoffice.org/#/admin/projects/bibisect-linux-64-5.3
In the table it has the comment: libreoffice-5-2-branch-point to latest master.

eyallior: try 5.2 from the below link[1]. Simply download it, set the executable attribute[2] and run. If it is broken, please retest 5.1[3] on your current machine so we can verify that it isnt something specific to your current machine, as it ran fine on your old laptop.

[1] http://libreoffice.soluzioniopen.com/old/LibreOffice-5.2.7.2.help-x86_64.AppImage
[2] https://www.youtube.com/watch?v=nzZ6Ikc7juw&t=1m16s
[3] http://libreoffice.soluzioniopen.com/old/LibreOffice-5.1.6.2.help-x86_64.AppImage

(In reply to Yousuf Philips (jay) from comment #13)
> eyallior: try 5.2 from the below link[1]. Simply download it, set the
> executable attribute[2] and run. If it is broken, please retest 5.1[3] on
> your current machine so we can verify that it isnt something specific to
> your current machine, as it ran fine on your old laptop.
> 
> [1]
> http://libreoffice.soluzioniopen.com/old/LibreOffice-5.2.7.2.help-x86_64.
> AppImage
> [2] https://www.youtube.com/watch?v=nzZ6Ikc7juw&t=1m16s
> [3]
> http://libreoffice.soluzioniopen.com/old/LibreOffice-5.1.6.2.help-x86_64.
> AppImage

Tried both:

5.1:
1) Can't use ctrl+c/ctrl+v/ctrl+a...
2) ctrl_arrow just doesn't do anything (can't even change the direction of the txt to right-to-left.

5.2
1) Can't use ctrl+c/ctrl+v/ctrl+a...
2) ctrl_arrows change text direction when I try to select whole words.

Well, both problems are duplicates:

(In reply to eyallior from comment #0)
> 1) No shortcut (CTRL+C/CTRL+V/CTRL+U) seem to work
Well known Unity specific problem, already reported in Bug 96022.

> 2) Trying to select whole word (CTRL+SHIFT+Arrow) causes text direction
> change
Already fixed in Bug 103158 for 5.4.0 and 5.3.4. Whoever affected can upgrade to the latest upstream release (either via a PPA or the upstream DEBs), to get rid of this bug.

*** This bug has been marked as a duplicate of bug 96022 ***