diff --git a/background.js b/background.js
index 32e72cb08830ac90d56f6db7ac8d2693467046a3..c4b361d6ecd38ae9a8f7120defe149a7c3ef98a8 100644
--- a/background.js
+++ b/background.js
@@ -54,7 +54,7 @@ else {
   else {
     console.log("Load default config");
     let headers = [];
-    headers.push({action:"add",header_name:"test-header-name",header_value:"test-header-value",comment:"test",apply_on:"req",status:"on"});
+    headers.push({url_contains:"",action:"add",header_name:"test-header-name",header_value:"test-header-value",comment:"test",apply_on:"req",status:"on"});
     config = {format_version:"1.1",target_page:"https://httpbin.org/*",headers:headers,debug_mode:false};
     // save configuration 
     localStorage.setItem("config",JSON.stringify(config));
@@ -92,7 +92,7 @@ function log(message) {
 function rewriteRequestHeader(e) {
   if (config.debug_mode) log("Start modify request headers for url " + e.url);
   for (let to_modify of config.headers) {
-    if ((to_modify.status==="on")&&(to_modify.apply_on==="req")) {
+    if ((to_modify.status==="on")&&(to_modify.apply_on==="req")&& (!config.use_url_contains || (config.use_url_contains && e.url.includes(to_modify.url_contains)))) {
       if (to_modify.action==="add"){
         let new_header = {"name" :to_modify.header_name,"value":to_modify.header_value};
         e.requestHeaders.push(new_header);
@@ -130,7 +130,7 @@ function rewriteRequestHeader(e) {
 function rewriteResponseHeader(e) {
   if (config.debug_mode) log("Start modify response headers for url " + e.url);
   for (let to_modify of config.headers) {
-    if ((to_modify.status==="on")&&(to_modify.apply_on==="res")) {
+    if ((to_modify.status==="on")&&(to_modify.apply_on==="res")&& (!config.use_url_contains || (config.use_url_contains && e.url.includes(to_modify.url_contains)))) {
       if (to_modify.action==="add") {
         let new_header = {"name" :to_modify.header_name,"value":to_modify.header_value};
 	e.responseHeaders.push(new_header);
diff --git a/popup/config.html b/popup/config.html
index c65651fa758e6e26977a9ba9f10edf232677d9db..7d63a5b7e4ac8c4cb60842824792db3e3b142213 100644
--- a/popup/config.html
+++ b/popup/config.html
@@ -59,8 +59,8 @@
 				<a href="#" id="import_button" class="btn btn-primary btn-sm" >
           				<span class="glyphicon glyphicon-import"></span> Import
         			</a>
-				<a href="#" id="parameters_button" class="btn btn-primary btn-sm">
-          				<span class="glyphicon glyphicon-cog"></span> 
+				<a href="#" id="parameters_button" class="btn btn-primary btn-sm"> 
+          				<span class="glyphicon glyphicon-cog"></span> Parameters
         			</a>  
    			</div>
 		</div> 
diff --git a/popup/config.js b/popup/config.js
index 806ca57547a1af4beca448a6e63f8a23a12963a0..43a20a43cb261e07ecc74ad3b7f4a8799250d2f0 100644
--- a/popup/config.js
+++ b/popup/config.js
@@ -33,13 +33,14 @@ window.onload = function() {
         }
 		
 	for (let to_add of config.headers) appendLine(to_add.url_contains,to_add.action,to_add.header_name,to_add.header_value,to_add.comment,to_add.apply_on,to_add.status);
-	document.getElementById('save_button').addEventListener('click',function (e) {saveData();});
+	document.getElementById('save_button').addEventListener('click',function (e) {saveDataWithWarning();});
 	document.getElementById('export_button').addEventListener('click',function (e) {exportData();});
 	document.getElementById('import_button').addEventListener('click',function (e) {importData(e);});
 	document.getElementById('parameters_button').addEventListener('click',function (e) {showParametersScreen();});
 	document.getElementById('add_button').addEventListener('click',function (e) {appendLine("","add","-","-","","req","on");});
 	document.getElementById('start_img').addEventListener('click',function (e) {startModify();});
 	document.getElementById('targetPage').value=config.target_page;
+	checkTargetPageField();
 	document.getElementById('targetPage').addEventListener('keyup',function (e) {checkTargetPageField();});
 	document.getElementById('exit_parameters_screen_button').addEventListener('click',function (e) {hideParametersScreen();});
 	
@@ -62,6 +63,7 @@ function showParametersScreen() {
 function hideParametersScreen() {
   document.getElementById('main_screen').hidden=false;
   document.getElementById('parameters_screen').hidden=true;
+  saveData();
 }
 
 function showCommentsClick() {
@@ -245,11 +247,13 @@ function isTargetValid(target) {
 * If url patterns are valid save the data to the local storage and restart modify header
 **/
 
+function saveDataWithWarning() {
+  if (!isTargetValid(document.getElementById('targetPage').value)) alert("Warning: Url patterns are invalid");
+  saveData();
+}
+
+
 function saveData() {
-  if (!isTargetValid(document.getElementById('targetPage').value)) {
-    alert("Can not save configuration: Url patterns are invalid");
-    return false;
-  }
   localStorage.setItem("config",create_configuration_data()); 
   browser.runtime.sendMessage("reload");
   return true;