I exported the colored notes to xml format and removed color tags. It is now fixed.

No, I don't use simplenote. But I might have tried simplenote sync before.

sure, I agree.
but if I want to extend the height of remark field for editing, it would be useful to keep the height fixed when switching between fields.

the highlight appears all by itself,
I have used cintanotes for long time before highlight feature was adopted in cintanotes. Several notes, maybe old notes, are highlighted whole note. I found it quite bothering.