Bread Using Water Roux

I have been making my own bread for several years and my goodness, silly me only found out about water roux recently while surfing the internet.  I tried it but I might have got it wrong though. When it was freshly baked, the texture was so soft and springy. However, come the following day, the bread has become a little harder.  Only the good old microwave will ensure that my family have soft and fluffy bread after MV-ing these babies for 1/2 min.

Guess I have to keep making more bread to get this right.  I really want that soft, fluffy and springy texture without using bread improver or bread softener.