that reads like you are just messing up when editing the file, adding (maybe invisible) characters
After editing, check and validate the kibana.yml with a tool, e.g.
or via command line with (eg) yamllint
This works for me:
# cat $HOME/.yamllint
extends: default
rules:
# don't fail if a line is long
line-length: disable
document-start: disable
comments: disable
# yamllint /etc/elasticsearch/elasticsearch.yml
# yamllint /etc/kibana/kibana.yml
#