*sigh* how often has this issue been told and told and told again...
changing the .conf file will NOT change the current channels setting, they are only for channel first initiation, after this the channel record is saved in .chan file and will overwrite all settings in .conf. You will best just do something like:
.chanset #mychannel chanmode +tnk-i key
The lifecycle of a noob is complex. Fledgling noobs gestate inside biometric pods. Once a budding noob has matured thru gestation they climb out of their pod, sit down at a PC, ask a bunch of questions that are clearly in the FAQ, The Noob is born