To amplify the view of any signal in Waves, simply highlight the desired signal(s) and select Tools -> Amplify Signal+ / Amplify Signal- from the top toolbar.
The keyboard shortcuts for amplifying signals are the '+' and '-' keys.
You can highlight multiple signals for amplification by holding the CTRL/CMD key and clicking on each signal name. You can highlight a group of signals in-line by holding the SHIFT key and clicking on signal names. You can highlight all signals with CTRL+a or CMD+a. You can deselect all signals with CTRL+d.
You can also amplify signal(s) by selecting the desired signal(s), right-clicking on the signal name, and selecting amplify+ or amplify- from the pop-up menu.
The expression for amplifying signals is =amplify(amount). http://support.initialstate.com/knowledgebase/articles/506811-expressions-amplify-amount