[Q] repalce setting.apk for missing android 4.2.2 settings? topic

Hi,
I recently got a cheap 7" tablet made in China.
It has android 4.2.2 but the manufacturer omit a lot of things:
1. no airplane mode to set
2. do not have the users tab in the setting

Is it possible to install another copy of, say, setting.apk to replace these functions?
And if so, how to do that?

thanks