1. Use must or have to is stronger than giving advice with should
2. Must vs Have to
2.1. Both used to talk about obligations. things you cannot choose not to do.
2.1.1. Must
2.1.1.1. This is more personal.
2.1.1.2. You feel that its necessary and important
2.1.1.2.1. You can use must to talk in formal or written English
2.1.1.3. Is about you and your feelings
2.1.2. Have to
2.1.2.1. This is more situational
2.1.2.2. Comes to a situation, not from you.
2.1.2.2.1. Its more common to use to talk in a daily conversation
3. Mustn´t vs don´t have to
3.1. It´s completely different to must and have to
3.1.1. Mustn´t
3.1.1.1. Talk about to things it´s forbidden
3.1.2. Don´t have to
3.1.2.1. It´s not necessary (you can do it if you want).
4. Must vs Should
4.1. Should
4.1.1. To give advice or express your opinion
4.1.1.1. You can only use shouldn´t to give advice or express your opinion
4.2. Must
4.2.1. Can also to give a advice
5. Must vs Have to vs should
5.1. Must
5.1.1. Obligations you feell strongly about
5.1.2. Obligations in formal written english
5.1.3. Strong advice
5.1.4. Say something is forbidden
5.2. Have to
5.2.1. Must obligation in spoken English
5.2.2. Strong Advice
5.3. Should
5.3.1. Giving advice
5.3.2. Giving negative advice
5.3.3. Giving your opinion