when a floating iceberg melts the water level remains about the same.
frozen water is less dense, that's why the ice is floating. ice does not displace more water than liquid water, unless you apply force to keep it down.
imagine pushing an inflatable ball underwater, stop pushing, it will pop up. same happens with icebergs. if not trapped they will pop up and
about 10 percent of its volume will be above sea level. that accounts for the density gradient between the solid and liquid phase.
you should worry about the greenland ice field melting and the patagonian and antarctic ice fields melting, that will have an influence on the sea level.
and don't pay attention to KittenKoder.