Most games from XSEED have a separate config utility which lets you configure input (and other) options. This one doesn't seem to have one. A shame really because the default controls are odd (to say the least). Circle is cancel, like I'd expect, but Triangle is enter, what?

Extremely late post but as no one has written anything yet, might as well.

As far as I know, the only way to actually change the inputs for the game would be checking out the corpseparty.ini file, but messing with those will always have a chance that it will mess something up, so I'd suggest against it if possible.

I installed the game again to see if I had a similiar issues with odd control mapping, to keep in mind I do use Xbox One S controller.
It had Cancel as B, which would be equivalent to Circle on PS4 controller, as well as A as select/enter, which would be equivalent to X on PS4 controller.

If you use PS4 controller (as I'm assuming now) without any additional programs for it, you could try to use DS4Windows or similiar program to remap the buttons so that it will work as you want in-game. I've had few issues where other games (Ys series for instance) messes up my PS4 controller's inputs so that the face buttons are in some weird order, like:
Triangle -> Square
X -> Circle

Using additional program for a game that doesn't have a simple way to remap controls in-game, has been the only option for me at times, so it's worth to try at least.

Thanks man. I don't know why I didn't receive a notification of a reply in this thread. I will checkout the ini file. I actually use a PS2 controller with a USB adaptor.

It's quite alright, hopefully it helps. If it doesn't, I can look into it more to see if I can find some additional info specifically about your controller.