Okay, but you should normally leave it at 60°C to kill off legionella.
So, it seems to me that you should be looking at the expansion/vent pipe arrangement. This is the pipe that travels up into the roof to above the level of the tank and then typically turns over and points down at the water surface but not submerged below it.
Have a look at where it passes through holes, e.g in the ceiling. If it can't slide a mm or two reasonably freely a slip-stick effect will cause 'banging' with whatever it's rubbing against acting like a sound board. There are all sorts of remedies, but they depend on the site-specific circumstances. You might, for example, have found a mysterious piece of hemp on the floor of the cylinder cupboard that was dislodged when you were swapping the shower. If so, it used to allow the pipe to slide as it passed through the plasterboard...
If this explanation seems reasonable to you (you're there and have heard the noise, we're not and haven't), we'll need some photos to advise further.
Or just get a plumber to sort it out for you. If you can produce the noise to order it will probably only take them a couple of hours, if that, to diagnose and cure. Get them to check your HW system temperature at the same time.