A: Well, it depends which version of The Computer you’re using. The bottom line is: check the language. Where it says “may” or “can” it means you don’t have to if you don’t want to. If it just says certain parameters are increased… they’re just increased, no choice about it.
For all versions of The Computer, the increase in Draw and Play quantity is required, which interacts with Play All But 1 to make it Play All – no choice for you. For the versions in Star Fluxx and both Star Trek Fluxxes, the Limit increase is optional, but for the promo card version and the Batcomputer, the owner must use the increased limits.
Note that BMO (Adventure Time Fluxx) has the power of optionally increasing Limits by 1, and Data (Star Trek: TNG Fluxx) has the power of optionally increasing Play by 1.
Star Trek Fluxx
Star Trek: TNG Fluxx