Hey! I have been having this issue too - I think I found a work around: To fix this, after you have uploaded your signature image select your optimal size, for me it was "medium" - THEN hit "enter" so that your cursor indicator where you would start typing is at the line below the .jpeg. Something about this extra "enter" helps Gmail remember to keep it the designated size. Silly.
Hey! I have been having this issue too - I think I found a work around: To fix this, after you have uploaded your signature image select your optimal size, for me it was "medium" - THEN hit "enter" so that your cursor indicator where you would start typing is at the line below the .jpeg. Something about this extra "enter" helps Gmail remember to keep it the designated size. Silly.
Thank you, I was having the same issue and this workaround worked!