This question was closed as off topic. LightDM login screen configuration

Now LightDM is used with ubuntu and Ubuntu Mate. The DM, greeter, and setting package are available in ubuntu.

The OP had said Debian Stretch, so as it states at the bottom of the close message, I edited the post to fit ubuntu rules: replacing "Debian Stretch" with "LightDM Greeter" since the question is about the greeter. Thus, making it pertain to ubuntu as well.

However, it was closed anyway. Although the OP wasn't using ubuntu, why deprive ubuntu users of the information they may want to customize their login screen?