My DD tells lies

[Dahelle]

How do I get my DD 11 to tell the truth? Any tips? My DD often tells lies big or small about things e.g whether or not she has brushed her teeth. Or a bigger one; secretly downloading an app she is not allowed by unlocking my phone to allow access. AIBU to think I need to put a stop to this now. How?! She told me today the lies just slip out and it’s hard for her to tell the truth. I have explained consequences for lying, set punishments when she has been caught out, praised truth telling! Talked about what happens to people who lie all the time (using real life examples). So now I am running out of ideas 💡.

Don't shame or punish her for lying; that just encourages her to be more sneaky than tell the truth.

Taking responsibility for the consequences is different than punishment. E.g. fixing a problem she's caused, but without making her feel small about it. Just matter-of-factly saying "I noticed X; how can I help you sort this issue out?".

Things like teethcleaning you'll need to consider going back to supervised brushing.

The phone thing, you'll have changed your password by now and reminded yourself that unsupervised access to the internet isn't in her best interests.

What natural consequences has she had to a lie?

These are strange and uncertain times, can you and her dad find time to have fun with her, be a bit carefree? (A big ask, I know, atm)

All kids lie at times but if it’s more than occasionally it needs nipping in the bud.
In those two examples I’d go back to supervised brushing and removing the phone or laptop or whatever it was the app is on for a set period - and changing the password on your own phone and not letting her use it. And when she gets her phone back telling her you’ll be making regular checks until you can trust her again.
It’s a tough one and if it’s not dealt with it will only get worse when she becomes a teenager.

@Papergirl1968 has it. Nip it in the bud while you still have control. Otherwise she'll spiral as a teen.