it takes time to achieve that 'broad' athletic look.. you have to put on a lot more weight. you can't just pick and chose to have a wide back and broader shoulders and think maybe that will add 10 pounds. it takes a lot more then that.
here is me years and years ago at 150 pounds with my skinny small back

now here is me at 210 pounds
I had to put on 60 pounds of weight in order to achieve a thicker broader look.. I couldn't of done it with just 10-15 pounds.
you have to just get bigger and stronger everywhere to get a thicker back and broad shoulders.. you have to get strong at your big compound lifts. my bench went from like 155 to 315.. my over head press went from 105 to 245.. on most all back movements and pulling movements I use the stack. I do heavy chest supported T bar rows with 4 plates.. when I do pull ups I do chest to bar (forget those half rep chin to bar pussy pull ups).
point is , heavy multi joint compound exercises build width and broad back and shoulders. don't waste your time with a lot of isolation stuff.
I've still got a long long way to go to get the truly wide back and broad shoulders I want. but over the years the progress I have made has been by doing things this way. get stronger and your back and shoulders will follow