Vertical axis

Hello, I am trying to use Excel in order to teach kids about functions. I would like to show the different graphs for the simplest functions such as direct proportionality. So for example if we draw the graph manually, we can see that if we change the formula from y=2x to say y=10x, the slope of the line changes. However, Excel rather changes the values on the vertical axis. Unfortunately I wasn't able to set it to changing the slope of the line, can it be done? I am attaching a screen.
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Thanks very much!