To zoom in on tracks or wave forms add the keyboard shortcut: Control + the plus key or Control + the minus key which is used in Windows to zoom in or out on web pages?

Some are having trouble with the mouse wheel function for this and would work if you were not using a mouse as on a laptop.
Carkins

Shift and + on my num-pad will zoom a selection on my desktop, don't have Biab on a laptop to try but maybe try num-lock first and see if that works.