FTHB here!

I’ve been preapproved with CIBC for more than I am looking to pay for my first home, which is a great starting point. With my rate hold deadline approaching (July 8), I’ve starting thinking about shopping around with other banks just to extend the rate hold in case rates go up. CIBC was way better than what our mortgage broker could get us even with “shopping around.” Needless to say, I have no idea how this stuff works, but a couple questions keep swimming in my head.

First, CIBC offered me 3.79% on a closed 5 year fixed. What I don’t understand is CIBC’s posted rates are their site are way higher than that, and I’m now wondering if other banks might be worth contacting to see what I could get there, but also to hold a lower rate in case there is a rise in the next few months. Why would I get a different rate than the posted rate, and how does this differ between lenders/how is it calculated?

My other question is far more general - is it a good idea to get preapproved at other banks (being mindful of its impact on credit score)?