Chart Y Axis

I am trying to get my chart to change the Y Axis automatically when the data is changed. For instance: If I have 10 periods of data for my X Axis, and my Y Axis ranges from 10 to 100, I would like for my Y Axis range to also range from 10 to 100. I really need help, and I know I didn't ask a very clear question, but if anyone could help I would greatly appreciate it. thx

Also if my Y Axis Data Chages from 100 to 100K I would like for my chart to change. Thanks again