It sounds to me like you have a digital therm.. they are super sensitive to adjust. but once adjusted, you usually never have to touch them again.
with all those styrofoam bators, they work best if you can have them in a warm draft free room..
and keep the away from any sunlight coming through a window..
do not plug up all the holes.. you have to have an air exchange or you can suffocate the eggs..
I like 60% humidity.. but do what works for you.. this is an area of large debate..
take your temps at the level where the eggs will be.. sometimes it may take up to four or five days to warm up the bator and stabilize the temp..
when you do open your bator here's a tip.. do not flip the top sideways or upside down.. you can keep a lot of warm air trapped under the top even though it is not in place over the bottom..
always add 101 degree water(or warmer) ( I add mine right from the tap at about 110 degrees.. the temp goes up for a few minutes, but that seems to do no harm..It is a quick way to raise the humidity..) so that the bator does not have to heat up cold water..
I have 8 of this style bators.. I have further modified them all so that I do not have to open them to add water or check temps..
.......jiminwisc.......