Consider the following snippet from Where Is My Mind (arranged by Maxence Cyrin). Notice how after the first few bars there's a time signature change. Does the key signature also automatically change here (so that all notes are naturals)?
I'm asking because at the beginning of the piece the time and key signatures are shown together, and when all the notes should be played as natural, only the time signature is shown. Therefore I'm wondering if, when later in the piece when only the time signature is shown, this is still the case.