There's no way I know of to prevent a 950 from eventually reaching Creators Update again. You can re-flash the phone with an older OS version easily enough (Windows Device Recovery Tool can do that, or you can do it manually to whatever build you find using
iutool.exe, which comes with WDRT). However, the phone will re-update back to the latest supported build, which in the case of the 950 is going to be the Creators Update. Re-installing the Creators update might produce a better-working phone - I had none of those problems with it on my 950XL, at least - but it also might not.
Have you tried a simple hard reset? Most of the time this will fix software issues. If it's actually a problem with the build version you're on, though (rather than the particular configuration of your phone on that build), that won't help. You could try joining the Insider program to get newer builds, but at this point in the release cycle the Insider builds are... not very suitable for use on a primary device.