If your environment is a non-Ambari based HDP, then you can manually edit the "hdfs-site.xml". These will be persistent.
If you are using a Ambari based HDP, then any manual editing of "hdfs-site.xml" will not take effect ( as the configurations are managed by Ambari and will not be persistent ). In such case, to have a persistent configuration, you will have to use Ambari to edit the existing properties or add new properties.
If you are using ambari, then you can't do changes from back end. If you update the properties from backend then it will not reflect in ambari. So you have to make the changes from ambari.
You can make the changes from ambari. (HDFS --> Configs --> Advanced).
Restart the services after you made any changes
And f you are using apache hadoop then you have do to changes from back end only, Restart the services after you made any changes
What kind of parameter you looking for go to
1) Login Ambari with Admin console -> HDFS ->Config -> Filter (Search for your parameter is exist or not )
If not exist, you can add directly to h
dfs-site.xml, it required restart of HDFC service (Namenode and Datanode)