I have checked all of them, I can research keywords but when I added them in a plan. I cannot delete or change from saved keywords.If you're having trouble changing the keywords in Google Ads Keyword Planner then
Check your Google ad account settings or
May be you have any browser issues....Make sure your browser is up-to-date.
Its weird, i never face this kind of things in my ad account. but let me checked once then i will definitely help you in this.I have checked all of them, I can research keywords but when I added them in a plan. I cannot delete or change from saved keywords.