Change default Docker registry

I’m just started to use docker(last version) and have some questions for configure docker registries.

  1. First of all, I haven’t understand how to change docker registry from default docker-hub to mine custom?
    I get tired to put docker registry before image name to pull it. If I can change default docker registry the problem will fix.

  2. In oldest version of docker was flag --add-registry for centos which can help me but it have deprecated now and docker don’t support it.
    I didn’t use this flag and this information from google. So maybe I can wrong about it

Can anybody help me?
ps. apologize for bad English)

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