There is considerable confusion about when to use shall and will. When I first learned English, the rule is that shall is used with first person pronouns (I and we) to form the future tense, while will is used with second and third persons (you, he, she, it, they), e.g.,“I shall be there but he will not.”

 

To express a strong determination to do something these positions are reversed, with will being used with the first person and shall with the second and third persons, e.g., “I will definitely go, and you shall go with me.”

 

These days, however, shall and will are used more or less interchangeably. The difference between shall and will is further weakened by the fact that we usually contract them in speaking (we'll, she'll, etc.). The interchangeable use of shall and will is now part of standard English.