In the Search menu click on Peak on Screen. This moves the data cursor to the highest waveform peak displayed on the screen in a selected channel.
OR
Double-click the left mouse button anywhere in the bottom annotation line. This will also move the cursor to the highest peak displayed on the screen in a selected channel.
Choose Search Peak on Screen (ALT, S, K). This also moves the cursor to the highest waveform peak displayed on the screen in a selected channel.