Какие части речи надобно согласовывать при переводе предложения из прямой речи

When we change direct speech into indirect we make some changes.

We change tenses. All present tense are changed into their past. But if the first part of the sentence is in present we dont change the tense in the second part.

He says I am going to the park now. He says he is going to the park now.

He said I am going to the park now. He said he was going to the park than.

We change pronoun. The first persons are changed into the third persons. This change depends on the contents.