Some params, like lruskips and lru2skips, can be changed online e.g. in promon or with proutil increaseto (with some restrictions). Most can't be changed online. In the case of lruskips its default value is 0, i.e. off. The startup parameter values you get when you start your DB depend on your OE version, obviously, and the proserve command line(s) you use to start your broker(s).
So if you set lruskips online, then stop and start your DB, if a value for lruskips isn't specified in your DB start script then when the DB comes back up lruskips is off again.