I suggest you download the Beolab Penta user manual from this site. Make sure that you download the correct version ie Penta I, II or III
Which type of cables are you using to connect the speakers to the amp?
Two types of speaker cables are available. Powerlink cables have 8 pin din connectors and if you are using these then you should set the speakers to L for left and R for right.
Alternatively, speakerlink cables use 4 pin din speaker cables and if you are using these then I will need to read the user manual myself as I cannot remember!!!