@wei123 - yes, please update KK2 to the latest version to fix the crash. Any particular reason you're using an old version?
@YooHei155 - you seem to be misunderstanding. In the world of computers there are two types of memory - transient (RAM) and persistent (HDD/SSD/flash...).
I'm talking about the former one. Cleaning up space from your device wouldn't help the cause (unless you have REALLY low space - though a couple of gb is more than enough). No files are created when you switch the language...
Which android device do you use to run KK2?