Enable Zsh prompt username
Solution 1:
The prompt is configured in your ~/.zshrc file setting the variable PROMPT. For example, to have your username and host followed by a "dynamic" %:
~ PROMPT="%n@%m%# "
romano@samsung-romano%
The whole set of customization is available in the, as ever, wonderful Arch documentation.
Anyway, I warmly advise the usage of liquidprompt --- notice that once installed it will install a mechanism to control the prompt so that changing the PROMPT variable will not work anymore.