How to make my meringues less sticky?
If the meringues are coming out of the oven sticky, you might lower the temperature slightly and extend the drying time (to avoid browning)--they should feel quite dry and very light coming out of the oven.

Sugar is hydrophilic--if the air is humid, any condensation--even when you cannot see it--on the meringues will dissolve the sugar, and then they will start to feel sticky, and the downward spiral will begin.

According to all my searching, it is best to make them on a low humidity day.  Of course, where I live in the summer, we pretty much don't get those.

If you are having trouble with them in storage, you might try to buy some desiccant packets, and put them in the container.  Most desiccant is not food safe, so it should not touch the meringue.  Amazon has lots of options.