So recently the size and placement of the UI has been driving me crazy! Mostly the 'new' relationship bit at the top center of the screen. Normally I don't notice the UI but I've honestly felt like I am looking 'around' it trying to see what my sims are up to. So I went on a search to figure out how to make it smaller.
Long story short:
Documents>Electronic Arts>The Sims 4>Options file> uiscale =100
The Options File is presented in rich text format... looks like a text file which opens with notepad.
I'm assuming 100 is the normal setting for my screen resolution which is 1920x1080 as that was what it was set at before I changed it.
So I change the '100' to '120' as the larger the value the smaller the UI appears in your game. I'm now a happy simmer again and can see a lot more of the screen!
Important Note:
Remember to quit your game before going into the files. Changing the UI scale size can cause paint by reference paintings to be blank and for some emotional painting auras to not work as normal. It can also cause issues with the photography skill. Changing the UI back to your computers default will cause this issue to not happen again and will allow emotional painting auras to return.
*Edited: This seems to be fixed with Update: 06/15/2017 – PC Version 1.31.37.1020 / Max Version 1.31.37.1220