Preface - I was flying online via VATSIM. LAX_CTR came online after I started the STARI was flying into LAX and was flying the YENNI ONE Arrival. I was bewteen PGS and CONDOR when ATC changed my route. I was given vectors to HEC then to turn direct to CIVET for the CIVET FOUR arrival.This is what I did.1. Switched out of LNAV and set heading to the vector to HEC2. Tuned HEC VOR flew inbound on the radial that most fit the vector.2.1 Went to myairplane.com and brought up the CIVET Four arrival3. Attempted to revise the routing in the FMCA. I deselected the YENNI ONE arrival and "EXEC'd"B. Could not find CIVET 4 listed as an arrival in the FMCC. Added CIVET as a FIXD. Went to the RTE page - saw that WP's for YENNI 1 still listedE. Erased YENNI 1 WP's - EXEC'dF. Attempted to add CIVET 4 WP's and could notG. Attempted to remove YENNI 1 from arrival - No luck4. Got really frustrated5. Flew CIVET 4 by hand - ignored the fact that ATC forgot about me while working out Comm problems6. Ended up about 1000' high at the end of the STAR7. Landed RWY 25L without any problem.8. Slept on the problem9. Posted this...Any suggestions?

Hello,to answer A and BAfter deselecting the YENNI 1 arrival if you would have entered either another arrival or runway the rest of the YENNI wp