You cannot observe amoeboid organisms without using a humidity or moisture chamber. This is basically a flat plastic box, the bottom covered with a thin layer of water and one or two posts or rails which carry the slides to avoid any contact with the water. The box is firmly closed with a lid and the water on the bottom prevents the microscope slides to dry out.
I store my moisture chambers on a window sill on the north, thus preventing direct sunlight to heat and destroy the organisms.
I always store my wet mounts in humidity chambers after a first observation. In this way I can find amoebae which were hidden in the debris during the first observation. After some hours or even days most of them come out of the debris.
These wet mounts can be kept well for several days or even weeks. Microgromia-species, for example, are hard to find in normal mounts, but in slides kept in moisture chambers, they multiply and built their shells on the cover glass, where they can be observed very easily.