On some phones, the Send button in BIG SMS can be hidden under the keyboard. This may happen when you write a new message and tap the text field: the keyboard opens and covers the button for sending the message.
Find the Send button position setting
To fix this, go to the BIG Launcher home screen, tap the three dots next to the clock, and choose “Preferences”. Then choose “Messages” and find “Message editor: Show send button”.
Choose Above the keyboard
This option has three choices: “Above the text”, “Bottom of the screen”, and “Above the keyboard”. Normally, “Bottom of the screen” works correctly. But if the Send button is hidden under the keyboard, try choosing “Above the keyboard”. Then return to the SMS editor. The Send button should now appear above the keyboard.
Fallback: show the Send button above the text
In rare cases, this still may not work. In that case, choose the third option, “Above the text”. When you return to the SMS editor, the Send button will be displayed above the message text field. This is only a fallback solution, but it can help on phones where the keyboard behavior is not standard.