Sorry for noob question here but im going crazy trying to find this option, sp the chart adjusts and fits screen automatically when you switch from 5d to 1h etc....
Hover over the vertical or y-axis
[depending on where you've pinned it, it's either on the left or right of the screen] > your cursor would change to an up-down arrow > right-click > tick the "Auto (fits data to screen)" option.