I referred you to other threads in your other thread...
How to read "あの人" ? Isn't it "a-no-hi-to"?
please try not to ask the same question more than once, it makes it hard to track the answers.
Glenn's assessment is correct, and there are some complicated rules for why and how sounds change in language, but in practice it's really not as complicated as it sounds.
say "hee hee hee" like you are laughing. Now bring the back of your tongue up and keep saying "hee hee hee." Only the back of your tongue should change position, everything else should stay the same. To make sure of this, try to keep the tip of your tongue touching your bottom teeth. When your tongue gets close to (but doesn't touch) the palate (hard roof of your mouth), the sound will change and sound KIND of like an "sh." Unlike the common "sh" sound in English, your lips will not be rounded. This is the Japanese /hi/ phoneme, you are now saying ひひひ, /hihihi/
now that you are making the proper /h/ sound, try putting "to" after "hi," If you try to voice the vowel and say it like "hee-to," you might notice that it's kind of hard and awkward to make those sounds together. Devoice the /i/, so ひ becomes more an aspirated sound. It'll start to sound KIND of like "shto," but remember your lips aren't rounded and the constriction is at the back of your tongue, not the front. Say it quickly several times. You are now saying ひと, /hito/.
These are three different sounds in Japanese that probably sound similar to you
しゅと /shuto/ - rounded lips, fricative with constriction at the alveolar ridge with the front of the tongue
しと /shito/ - unrounded lips, fricative with constriction at same placement as above
ひと /hito/ - unrounded lips, fricative with constriction at the palate with the back of the tongue
try to practice those sounds until you're comfortable with them. Then it'll be easier to hear the difference when people are talking