Both glass panels should "tilt" if you push the button. (also known as the "vent"position).
It should open to the comfort position if you slide the Button backwards once, it should open completely if you slide a second time. All these is in the manual.
There's no way to prolong the life of the sunroof that I know, I just use it regularly, it works perfect every time.

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"If everything seems under control, you're just not going fast enough"
-Mario Andretti.
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River City Bimmers Chapter
2005 X3 3.0i ZPP, Htd seats, Htd strng, Black Sapphire on Terracotta.
1995 ///M3 Coupe, Lux, MT, Htd seats, Cosmos Black on Black.