I just don't understand this they don't ever seem to drink their water, what can I do to get them to drink it??

It may seem barely noticeable whether or not they're drinking, as far as the water bottle is concerned. You could draw a line on the bottle, and check to see if the water level drops.

If you're concerned that they might be getting dehyrated, try the "tent test." Pinch the skin between the shoulder blades and pull it gently. If it stays tented, they're dehydrated.

Gliders are sap suckers, though, and get a lot of their moisture from their foods, especially the fruits. If you're feeding watermelon, for instance, they'll get a lot of their water from that.

Gliders do not really drink that much water. The majority of the water that they need is in their food. They usually will not let themselves get dehydrated if water is provided. If you are using a water bottle you could try putting the water in a dish and see if that is more readily accepted.