Choose Format - Arrange - Send Backward (LibreOfficeDev Writer, LibreOfficeDev Calc).
Choose Shape - Arrange - Send Backward (LibreOfficeDev Draw).
KomandaCtrl+minus znak (LibreOfficeDev Utisni, LibreOfficeDev Nacrtaj)
Open context menu - choose Arrange - Send Backward (LibreOfficeDev Impress).