To try to help you understand - had you written this in key Am, the notes would be ABCDEFG. Making them all sharp takes the 'E' to E♯, while the F becomes F♯.
However, as Aaron states, that key, same sounding notes in 12 tet would be better known, written and read as B♭m. Reason being, two fewer 'accidentals' in the key sig.
So many questions here seem to be ...
The A# minor scale is more typically written as Bb minor -- A# and Bb being the same pitch.
Bb C Db Eb F Gb Ab Bb
A# B# C# D# E# F# G# A#
Note that the two scales comprise the same pitches, spelled differently, and in particular F and E# are equivalent.
One can certainly use pitches that are out of the main key -- or even change keys ...
It is ok to mark the lines and spaces as a reminder, but like Tim says you should play the scales and fundamental chords of each key before reading and practicing a piece! The goal is that you will train your ear and hear immediately when you miss an accidental or a key assignment, because you are "in the key" and know which is the home chord and ...
The primary thing is to establish key notes before even trying to play. So work out what key the piece is in, then run up and down the scale involved, also arpeggios of at least I IV and V, hands separate and together if you can. That puts you in the right ball park for most of the notes - and tells which notes probably won't be played.
You won't be the ...
If you have to do things like this in the beginning that's totally fine! It's awesome that you are learning and trying to improve.
The first thing I would recommend trying to slowly ween yourself off is writing in the key signature. When you feel ready, try looking up what the scale of that key signature is, and practice playing the scale, getting use to ...
Key is the root note (first note you start playing or singing the song) or tonic
scale is collection of notes with their own pattern
you can test it here
the scale you choose with the tonic (key), it will show different result (scale pattern because each scale have it's own unique interval ...
Key (location in sound) - Root Note
Mode (flavor or color) - Set of notes or interval pattern stacked on top of the root noted.
You can play Key of "C (Major)" (all white keys) without sharps or flats (black keys). But you're simultaneously kinda playing 7 modes (flavors).
All white keys!!!!!!!!!!
C to C is Major
A to A is minor
B to B is locrian