Question

when should i use 'assure', 'ensure' and 'insure' ???

Answer 1

Insure relates to the buying and selling of insurance. However, people can also use it to mean "to make sure of something."
ensure has a very similar definition to ensure-"to make something certain or safe"
Just like insure and ensure, assure means "to make a statement for the purpose of inspiring morale or belief in someone or to make someone confident in their beliefs and ideas."