A Query about Musical Sharping

[Venger]

Not too long ago I went over major scales in my mandolin music book. It was easy enough to understand and master, but I came across a snag. In the music book, it lists the G major scale, for example, as covering a certain octave, starting on the second to bottom line on the music staff and concluding on the in-between-space above the top line. Now the mandolin can cover some 2+ octaves, so I can play this particular scale one octave lower. But do I still sharp the F? As any competent musician knows, in the specific case of the G maj scale, the F note is sharped. But how often is it done so?
I think I already know the answer to this, but I have some confusion when it comes to denoting a specific scale on a musical piece. Again, back to the G maj scale, it is denoted by placing a sharp symbol on the top line, in between the treble cleff and time signature. But suppose in that musical piece I should be required to play an F note, one that isn't on that top staff line? IS it still sharped? Short and sweet of it, if I am playing any music piece "in key", is every note that is denoted sharp always played as sharp, regardless of where it falls on the staff?

Hopefully you understand my confusion and question. Because though I am at least familiar with music, I am not the one some one should come running to for help. Hence this.

As always, thanks for the help I know you will give.

[Jakarius321]

If the key signature says that F should be sharp (in G Major's case on the top line of the treble clef) then any F you play is always sharp unless marked as natural ♮ .

So if I've understood your question correctly then yes any note denoted to be played as sharp or flat by the key signature should be played sharp or flat unless specified otherwise by a natural sign (but you don't get naturals in scales I don't think).

EDIT: Regardless of where it is on the stave.

[Venger]

Thanks Jak. Like I said, I surmised as much already. And from just twiddling around I knew it just "sounded right" if I sharped ever F (in G maj case). But still, I felt the need to confirm my assumptions.

[Jakarius321]

Hey no problem, this sort of theory sort of gets drilled into you when you have to practise a multitude of scales over 3 octaves for Grade 5 piano

[Musicman247]

Great answers! Key signatures cover every note played in a piece unless the note is preceded by an accidental.

My work here is done