If it not a version 6: when the HMI powers up, press the small white square that appears in the lower left corner. I haven't seen that square in version 6 panels (or have missed it).
For anyone interested, here are the direct links from the Knowledgebase for both the older PanelView Plus terminals (pre PVP 6), and the newer PanelView Plus 6 terminals:
Older PanelView Plus terminals: 41070 - PanelView Plus Configuration Mode for firmware version 4.00.12 to 5.1x
Access Level: TechConnect
Newer PanelView Plus 6 terminals: 119811 - Getting to the configuration screen on PanelView Plus 6 terminal
Access Level: TechConnect