Sometimes, without a bit of further setup, your Neurokeys keyboard will switch back to the native one, without a reason (especially in some Messages app and Safari). 

There is a solution to this. 

For iPhone users: 

- Go to Settings > Keyboards > Press Edit
- Drag Neurokeys to the top of the list
- Press Done to confirm changes
- If the issues persists, you can "Disable" the native keyboard by swiping left. Don't worry, your native keyboard is never really gone. 

For Android Users:

-Press the space bar button for a few seconds
- Pop up screen appears
- Select Neurokeys Keyboard

Note: One exception, When you are entering a password, the keyboard will still automatically default to Apple's standard one. 

It will, however, switch back to the Neurokeys keyboard after you exit the password field.