where in the app can you adjust the serving measurements

I am starting keto ..the food is fabulous..i feel like im gong back to school to learn about nutrition..its fascinating,,,,,,i have used the smothered chicken recipe under chicken  and its was incredible i did know  food could taste so good....im joining  premium when  get my social security check..

My question is where can I adjust the serving ex ; for butter  sour cream cream anything..?anyone have a hint .Thank you in advance  Chris