How to change my profile picture on Facebook to an older one, but keep the likes? - 1

I am still kinda new to Facebook.
For example. Yesterday I updated my profile picture on Facebook (picture a), but later I realised that I want to change it back to my last profile picture again (picture b).

Picture B has about 400 likes on it, whereas picture A has about 70. How do I change back to picture B but keep all 400 likes?

(Please let me know if you are using an iPhone, iPad or computer to do this.)

Thanks!

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