- "Someday" always refers to the future, but
- "One day" can refer to the future or the past.
Please use English well!
The global average TOEFL speaking score is 19. The Japan average score is 15. My students' average top TOEFL speaking score is 23. Why? Because they don't use templates! If you have a clear voice and practice regularly, you should get 23 consistently too.