In Atomic Wallet, to export your private keys go to "Settings" -> "Private keys" and Insert your password.

You will see the list of private keys. To copy your private key -> just click on it.

Then paste it in any other wallet that support the coin that you're want to export.

If you want to export Monero (XMR), you will see two private key in two lines:

First line is a Private View key.

Second line is a Private Spend key.

In the meantime, check out our XRP Wallet