The problem is that the Surface Pro 4 has a 2736 x 1824 resolution 12.3" screen. That is a very high resolution for such a small screen. The higher the resolution, the smaller text and other things will be.
I think 150% scaling is typical when using laptops with very high resolution screens, but in your case I suppose you had to bump that up to 225%. Programs need to be designed to take advantage of Windows scaling. If they don't then the icon and text will simply be displayed at 100% (which is normal) which means they will be hard to read / see.
It appears the version of QuickBooks you are using does not support scaling. Maybe they have a patch update for it on their website to fix the issue. Or the scaling support could have been implemented in a newer version of QuickBooks which means you would need to upgrade from what you have.
If there is no patch update for the current version of QuickBooks / a newer version of QuickBooks that supports scaling, then you would need to lower the screen resolution until you can use QuickBooks comfortably. That could be 1920x1080 or 1600x900 resolution or below; depends on you.
Lowering the desktop resolution will mean text will not look as sharp as before. The lower the resolution, the more blurred / soft text will be.
Alternatively, you can return the Surface Pro 4 and buy a larger laptop / 2-in-1 convertible with a 1920x1080 resolution screen so you do not have to deal with scaling issues... unless the text is too small for you to see at that resolution on a 13.3", 14" or 15.6" screen.