Becoming Executer of a minor's estate

My two minor children have money left to them from their fathers life insuance policy. The accounts are both 1% interest bearing and I am not able to transfer to another type of investment or account with a higher interest rate until I become the Executor of their Estates. My older son who is 17 would also like to access a portion of his funds to purchase a vehicle before he is 18. How do I go about becoming the Executor of their estates?

[randalljd]

Who is responsible now? Who is managing the accounts?

I am the legal guardian of both boys. However the life insurance company has put the money into separate 1% interest bearing accounts that are part of their own company. They wrote me a letter stating that I had to become Guardian of their Estates before I could access the monies for them. I want to put the younger boys money into a higher interest bearing account, he is 15 (7-12-91). The other boy is 17 (1-16-90) and wants to purchase a car and invest the rest. I just want to make sure that they can access their money when it is necessary and want the money to earn a higher rate of interest. Also, is 18 the age of dispersment? I wasn't sure if it was 21.