The latest update contains an additional menu control called "Level 1 Capacity".
https://imgur.com/a/P1rSBkX
If you've ever leveled up a bunch of level 1 hiragana/words all at once, you may have felt a bit overwhelmed at the end of the battle when you learned an equal number of new hiragana/words.
By default "Level 1 Capacity" is set to 7. You can now take it down to 5 which may be more manageable for some people. In other words, rather than learning 7 new words/hiragana in parallel, you should never be faced with more than 5.
Happy learning!
Lun