In case if used needs to modify settings from default there is impossible to change fields "severity", "new issues only", "new lines only".
Steps to reproduce:
1) go to

{jenkins url}/job/{job name}/configure
2) change mentioned above plugin settings (make them different for default values which are: Severity = MAJOR, New issues only = true, New lines only = true);
3) save changes
4) return to {jenkins url}

/job/

{job name}

/configure

ER: saved values should be shown
AR: default values are shown.

This bug does not affect plugin execution for fields Severity and Changed Lines Only: saved items are used for execution.
New lines only used as false regardless of saved value (this also should be fixed).