It is more than common to have noisy pipes at your house, and many people solve that problem differently.
Someone prefers to turn the volume up while taking their morning shower another just silently ignores it. And here is someone who wants to fix it.
Copper pipes that used for residential plumbing tend to expand from heat, so if you using hot water the diameter of the plumbing pipe increase. When it cools off it comes back to it is usual state. And it is absolutely normal.
What you could do about your hot expanded copper pipe? Absolutely nothing, but get it to the fixed position. Like you could attach the pipe with a special plumbing clamp to a joint or drywall. There are many kinds of it, in the nearest hardware store for sure you would find exactly the one that fits you the best.
Also to make pipe fit tighter and reducing possibility to make any noise, you could buy adhesive backed felt, line the clamp with it and that's it! There might be a place where two pipes go close together or cross each other, you may find necessary to wrap pipes with adhesive-backed felt there as well.
Hope this little simple tricks would help you to make your home to feel more like a home.