"i was told" or "i have been told"?

I think it depends on the sentence.

Preposand if i want to continue one of these sentence, should i put a "that" after "told" or just omit it?

thanks.

I usually use "that" in writing, but I probably omit it often in casual speech.

Why the "that" can be omitted and depent on which part of the sentence?

I don't really understand why a relative pronoun can be omitted.

PreposWhy the "that" can be omitted and depent on which part of the sentence?

I don't really understand why a relative pronoun can be omitted.

I think it would help if you could write some sentences showing what you are trying to understand.

I was told nothing/I have been told nothing
I was told to go home/I have been told to go home