[Best way to decrease queue wait time?]

On my log flume, the wait time is 15 mins. How should I change the minimum wait time or anything else to decrease this?

[Game thinks entrance hasn't been built and won't allow me to Test/Open]

New to this game, and I built my custom roller coaster (the mini roller coaster). However, I've been trying for an hour to test or open but I can't because the game says "entrance not yet built despite me having placed one in every possible position and orientation. Screenshot attached.

Am I doing something wrong? Help much appreciated.