Your notation is really a natural minor of E. Katyusha sounds lyrical and soft in minor, but it is not gorgeous in major. When you say staff key signature, is it key signature in G major? Can I put pictures? I saw a staff member. I don't know if it's the one you said. Key signature is two flat numbers, and the mode is changed to G natural minor, so it ends with 5.

The notation adopts the method of naming the first note, and the scale of notation is1234567 no matter what the tonic is; The staff adopts the method of fixed tone roll call, and the tone from which the scale starts as the main tone is fixed. For example, the scale in C major is CDEFGAB, and the scale in G major is GBC DE # F.

In the example of notation, 1=G, that is, the tonic in the staff is g, and the scale in g major is Gabcde # F, which corresponds to the scale in notation 1234567. It can be seen that 1=G, 6=e is a natural minor.

7 and 3 are key signature in B flat major, and the scales in B flat major are BCD and EFGA, which correspond to the scale of notation 1234567, 1= B flat, 6=g, so it is the natural minor of G.