I've been attempting to pick up my music theory after a 1 month hiatus, and I've stumbled across transposing key signatures - is there a quick method of figuring out the new key signature? Because right now I'm transposing every note of the key signature to find out the new key signature - but I feel like there's a much quicker method to do so. Right now I can't be completely certain of a new key signature if a couple of newly transposed note fit it - because I don't know whether there will be 2 notes that might not do so. Help will be appreciated, thanks!
EDIT: If you don't understand - what I mean by transposing key signatures is by transposing each note of it up or down by an interval such as a major 2nd - such as how if you transpose C major up by a major 2nd it becomes D major. To clarify - I am not struggling with the transposition of key signatures - I am struggling to do it quickly. An example would be where I transpose E minor up by a minor 3rd to find the new key signature - it would take me at least 10 minutes to do so.