When a key has sharps or flats, it is notated on the staff at the beginning of each line as a key signature.
A key signature tells the player which notes are to be sharpened or flattened throughout the piece. It includes those notes across all octaves, not just the note where the key signature is placed. This is to avoid the use of accidentals written before the note in every bar.
The key signature is a set placement of sharps or flats and must be written the same way all the time. There is no variation so it must be memorised.
Major Key Signatures with Sharps for Treble Clef
Major Key Signatures with Flats for Treble Clef
Key Signatures for Bass Clef
To write your key signatures for bass clef, you follow the same order of sharps and the same placement but shift the key signature down a line/space.
G Major – Treble Clef
G Major – Bass Clef
A common mistake for key signatures for bass clef with 5 or more sharps, is to place the A# on the top line, but that is wrong to do so.
Following the above process, A# will always go in the bottom space for bass clef key signatures.