I guess this feature is not yet ported to 4.0..
From documentation:
"Some of the features/settings which were part of the previous versions of the Edwiser
RemUI are temporarily unavailable in the Edwiser RemUI 4.0 and would be introduced in
Edwiser RemUI upcoming releases."
RemUI changelog here: https://edwiser.org/documentation/edwiser-remui/change-log/