There are possibilities as follows.
- Caps Lock is ON
To switch ON/OFF Caps Lock, hold down the [Shift] key on the keyboard and press the [Caps Lock] key. - “All caps” option is ON in Microsoft Word font setting
The “All caps” option is toggled ON/OFF with Microsoft Word keyboard shortcut [Ctrl] + [Shift] + [A]. If you encounter such a problem on Word, you may have pressed this keyboard shortcut without noticing.