Made for a younger crowd

I was able to bluetooth to my Iphone, but I can barely read the directions because they are so small.  The unit is very small, but the sound is good in relation to the size of the speaker.  Most of the reveiws on Amazon are actually for a phone charging unit.  Not sure why?  I looked for reviews online to figure out how to string the 4 units I bought together to play the same music throughtout my home, but no can do.  Hoping to find a savvy young techy to help me figure out these 4 units.  https://smile.amazon.com/gp/product/B077GQWGHP/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1