If you want to check how a broadcast will look on your phone before sending it out to your audience you can send a preview to your phone.
Don't know what Broadcasts are? Please read the Broadcast Overview documentation.
To do this click the 'Send preview' button whilst composing a broadcast.
If you open the app on your phone you will have been sent a preview version of your broadcast.
When you've finished checking your preview you can dismiss it as you would any other broadcast by swiping down or by clicking "End preview".
You can carry on editing the broadcast, and then send another preview as many times as you like until you get it just right. Then send your broadcast as usual.