I'm studying as an exchange student from the US to Quebec (Canada) for 4 months, but want to stay longer [closed]

So, I will be on exchange to Quebec (Montreal) from January to April 2018. That is, the trimester will last January through April. I have verified that I don't need a study permit, as I will not be there for more than six months, and I don't intend to work while I'm there.

However, I would like to stay for an extra month if I'm there, or stay the whole six months. As I understand it, the border officer will decide the length of my studies:

A border services officer at the port of entry in Canada will determine how long you can stay in Canada. Most visitors are allowed a six-month stay from the day they entered Canada. If the officer authorizes a stay of less than six months, they will indicate in your passport the date by which you must leave Canada.

Would anyone happen to know what circumstances would arise that I'm only allowed the 4 months? I know my home university won't be regulating my stay, and neither will UQAM.

As an American, I do not need an eTA or visa for a stay of under six months.

Edit: to clarify, I will not be moving here permanently. I will only be on exchange for one trimester (4 months).

Edit 2: trimester, not semester.

Thanks for your help in advance!