Is it very humid by where you are right now? High humidity will definitely affect the dehydration process. The humidity by me is very high right now, so I haven't done much food drying at the moment. Just check your local weather and the humidity levels should be posted. Humidity levels really do make a difference.
My dehydrator has a thermostat (heat adjustment) on it, and it says to dehydrate fruits at 125 Fahrenheit. You could preheat your dehydrator and use an oven thermometer to get the heat right, then place your fruit in it.
Try slicing your strawberries in 1/4" pieces to get a more even dehydrated fruit.
I've only had my dehydrator since this January, so I'm no expert by any means. I've mostly dehydrated fruit & veg, but have also done a couple tries at beef jerky.
Hope this helps.
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