The project of the altimeter is shown in hectopascals (hPa, 1 hPa = 1 mb) or inches of mercury (inHg in Anglo Saxon countries).

Example: 1030 hPa = 30.41 inHg.

The numbers are very small panel in the two measures of
QNH,

Placing the mouse over the clock Altimeter but is a sign the measure, inHg, for example:
30.41 inHg.
How can I change the title to the extent hPa, for example: 1030?
Frangollo