Matrix

Glad that it worked!

Don't forget to set up secure backup, though!
For the sake of simplicity I didn't tell before, but without that you can lose keys when you stop using an old device of yours.
This is because your old device may contain keys that other devices don't.
Your new phone, but generally every client app only downloads encryption keys for messages that it has tried to load at least once. This means, your new phone does not have the keys for old messages until you scroll up to all of them, and if you log out of your old device, or factory reset or lose it, you will lose those keys.
But when you set up secure backup, it uploads all of the keys to the encrypted backup store, and you'll not lose any of them.