piano roll editor (the old one)

The old PRE was not documented with a reason. It was not very powerful and had known inconsistencies/problems. The new one is documented, because it is much more powerful and polished.

If you are on an old version of MuseScore and want to access the old piano roll editor, right click on an empty part of the staff and chose Piano Roll Editor from the drop down list.

You wrote:
there is no search on this forum, i keep getting sheet music

See image below:

Regards.