@OP this is the wrong board,
move it as suggested by @Little Mouse
i have 5 account on my metamask desktop, but when i add in smartphone using private key, only the first account is added,
how add multiple accounts?
That is not the way of how it works. Each address(accounts) consist of a different private key. So, you had to do import them one by one. Instead, the favourable/best way is to import your seed phrase to your mobile applications.
The seed phrase/12-word secret recovery phrase is the one that is able to hold many addresses(account), by importing the seed phrase into your mobile, it will automatically show all of your accounts, so you don't have to import the private key one by one.
You can just sync your metamask
That's exactly what I had in mind when I first used Metamask years ago.
As of now, Metamask disabled the QR sync. So importing the seed phrase is the only viable option.