This was from older version and still happens even in the latest version of minecraft so basically When a player is not signed in with a Microsoft/Xbox account and changes their game settings (like sensitivity, FOV, or controls), those settings 'do not save' after restarting the game. Once Minecraft is reopened, all settings return to their default values.
MCPE-205699
Settings reset to default after restarting Minecraft [when not signed in].
Resolved
Duplicate
0
Steps to Reproduce:
1. Open Minecraft (not signed in).
2. Change a setting (e.g., lower FOV or change controls).
3. Close and restart Minecraft.
4. Notice the settings have reset to default.
Expected Result:
Settings should stay saved even if the player is not signed into an account.
Observed Result:
All settings go back to default after restart.