Hi, thanks for the reply again, but I still don't understand why you can't change the tense for the infinitive if you want to. Just because it sounds strange doesn't mean it's wrong, after all. Perhaps you can address this by way of an explanation? Another example is 'he wanted to go to the fair to buy cheap food.' Should this be converted to 'he had wanted to have gone to the fair to have bought cheap food' or 'he had wanted to go to the fair to buy cheap food'? Logically it makes sense for all the tenses to change together.

If it sounds strange, it usually is wrong. I think that's the first point. Remember, grammar rules are a set of rules borne from what people have said over the years. It's not the other way around.

That said, the issue here is that your other "verbs" are not verbs. They are infinitive phrases which are playing the roles of nouns, adjectives or adverbs. (Hopefully, the link will help in the explanation.)

That's why they don't change like the main verb.

I hope that helps.