how do i change the lot type in sims 4 after the update last week?

What you need to do is click on the lot you wanna use, and click 'Build Mode'. Then on the top left hand corner, there will be a bit which says 'i' and click on that. Then click on the lot type (where it says 'Residential') and then you can change it. The game will give you a checklist of items which you need to fully make it, I've done it before and made a pool myself, which attracted many sims! 

Happy simming!