Rookie Question, maybe

Try them all and use the ones that sound best to you.  There is no right or wrong.

Thanks.  I just want to make sure that I am not going any damage to either the speakers or the Amp, mostly the amp.

It’s my understanding that the 4ohm and 8ohm Connections on the tube amp will allow safe power supply voltage for speaker load.  I think it’s based on different taps for the output transformer.  So, if you have 4ohm speak res, connect them to the 4ohm binding post on the amp.

Welcome to Audiogon. You are going to find that you will get a variety of opinions on any topic or question you post. I consider that a good thing, but as you can see you already received two different answers that could have you going two different directions. Here is my advice: Read the Prologue manual (hard copy or online) to determine whether it specifically says you should not connect 4ohm speakers to anything other than the 4ohm posts. If it doesn't tell you to expressly avoid such connections, then I would try them all and see what sounds best to you. This is a hobby. As such, you should try different options when they are available unless they are patently dangerous, will void the warranty, or you're not sure if it will damage the equipment. I would be surprised if trying your speakers on all the optional speaker posts will hurt either your speakers or your Prologue.
Have fun
Al