writer-tools - mail merge wizzard

Hello!
Please, if I do anythnkg (merging documents) after tools - mail merge wizzard- I simply cannot make CHANGES.
If I want to change anythhing, then it makes a change, at the certain STEP, but FINAL DOCUMENT IS THE SAME, as if I did not make a change.

Please, is there a solution, or is that just bad instable pc?
Cannot reach another to check at the moment!
Many thanks!