The traditional rule is that shall is used with first person pronouns (i.e. I and we) to form the future tense, while will is used with second and third person forms (i.e. you, he, she, it, they).

Where we use shall and will?

As a general rule, use 'will' for affirmative and negative sentences about the future. Use 'will' for requests too. If you want to make an offer or suggestion with I/we, use 'shall' in the question form. For very formal statements, especially to describe obligations, use 'shall'.

When to use would will and shall?

Will and shall: form

Will and shall are modal verbs. They are used with the base form of the main verb (They will go; I shall ask her). Shall is only used for future time reference with I and we, and is more formal than will.