[Q] Change lock screen app topic

Hello,

I am trying to change my lock screen app, from the standard one to Picturesque, the new one from Microsoft. But when I install it, it only shows up a few seconds after unlocking my phone. I first get the standard Xperia lockscreen and after 1second it swaps to the new lockscreen app.

Is there any way to change this? The 1 second wait makes it totally useless as a lockscreen replacement.

So how do I get rid of the xperia lockscreen and replace with my own custom lockscreen app?

Thx a lot