Did you make the config change before or after you started ingesting data? Existing indices won't be affected, so you would have to perform a manual rollover on your APM index aliases (apm-7.15.1-transaction, apm-7.15.1-span, ...). See Rollover API | Elasticsearch Guide [7.16] | Elastic for how to do that.
@axw As I use Docker, I just completely wipe out elastic volume's and built APM image (as i'm copying config inside of it in docker file) Seems nothing to change. only Elasticsearch has persistent volume configured. So a bit confused. Will try this. Will write if it work thanks!