The problem with aluminum is that it expands and contracts with the changing weather. There is nothing that can be done about that, other than changing the eaves themselves. The problem, however, may lie in the type of sealant you are using on the seams. If your eaves are expanding and contracting, then you should use a sealant that also expands and contracts. The best one to use is polyurethane caulking, which is designed for roof flashings and moves with weather changes. Scrape the aluminum very clean before applying the sealant.