diff --git a/src/BiliPlus.py b/src/BiliPlus.py
index 9fd7eea..631aeba 100644
--- a/src/BiliPlus.py
+++ b/src/BiliPlus.py
@@ -57,8 +57,8 @@ def __init__(self, comic_id: int, mainGUI: MainGUI, save_path: str = "") -> None
             "1400avif": "avif-1400w",
             "1100avif": "avif-1700w",
         }
-        img_format = self.mainGUI.getConfig("img_format")
-        self.headers["cookie"] += f"manga_pic_format_http={img_format_list.get("img_format", "jpg-full")};"
+        img_format = self.mainGUI.getConfig("img_format", "default")
+        self.headers["cookie"] += f"manga_pic_format_http={img_format};"
 
     ############################################################
     def getComicInfo(self) -> dict:
diff --git a/src/Episode.py b/src/Episode.py
index 6e97bbd..70ff740 100644
--- a/src/Episode.py
+++ b/src/Episode.py
@@ -248,7 +248,7 @@ def _() -> list[dict]:
             "1400avif": "@1400w.avif",
             "1100avif": "@1100w.avif",
         }
-        img_format = self.mainGUI.getConfig("img_format")
+        img_format = self.mainGUI.getConfig("img_format", "default")
         imgs_urls = [img_url + img_format_list[img_format] for img_url in imgs_urls]
 
         # ?###########################################################
diff --git a/src/ui/PySide_src/mainWindow_mac.ui b/src/ui/PySide_src/mainWindow_mac.ui
index 82bbc5f..c3c7437 100644
--- a/src/ui/PySide_src/mainWindow_mac.ui
+++ b/src/ui/PySide_src/mainWindow_mac.ui
@@ -1217,7 +1217,7 @@ li.checked::marker { content: "\2612"; }
                 <number>2</number>
                </property>
                <property name="value">
-                <number>16</number>
+                <number>1</number>
                </property>
                <property name="orientation">
                 <enum>Qt::Orientation::Horizontal</enum>
diff --git a/src/ui/PySide_src/mainWindow_ui.py b/src/ui/PySide_src/mainWindow_ui.py
index 6c26603..891681b 100644
--- a/src/ui/PySide_src/mainWindow_ui.py
+++ b/src/ui/PySide_src/mainWindow_ui.py
@@ -869,7 +869,7 @@ def setupUi(self, MainWindow):
         self.h_Slider_num_thread.setMaximum(32)
         self.h_Slider_num_thread.setSingleStep(2)
         self.h_Slider_num_thread.setPageStep(2)
-        self.h_Slider_num_thread.setValue(16)
+        self.h_Slider_num_thread.setValue(1)
         self.h_Slider_num_thread.setOrientation(Qt.Orientation.Horizontal)
 
         self.h_Layout_num_thread.addWidget(self.h_Slider_num_thread)
diff --git a/src/ui/SettingUI.py b/src/ui/SettingUI.py
index de1d080..a1836ea 100644
--- a/src/ui/SettingUI.py
+++ b/src/ui/SettingUI.py
@@ -622,8 +622,8 @@ def init_img_format_setting(self) -> None:
         }
         reversed_img_format_list = {value: key for key, value in img_format_list.items()}
 
-        img_format = self.mainGUI.getConfig("img_format")
-        self.mainGUI.comboBox_img_format.setCurrentText(img_format_list.get(img_format,'default'))
+        img_format = self.mainGUI.getConfig("img_format","default")
+        self.mainGUI.comboBox_img_format.setCurrentText(img_format_list.get(img_format))
 
         def _(img_format: str) -> None:
             self.mainGUI.updateConfig("img_format", reversed_img_format_list[img_format])
@@ -668,7 +668,7 @@ def init_recursive_read_setting(self) -> None:
         if flag is not None:
             self.mainGUI.checkBox_recursive_read.setChecked(flag)
         else:
-            self.mainGUI.updateConfig("recursive_read", True)
+            self.mainGUI.updateConfig("recursive_read", False)
 
         def _(checked: bool) -> None:
             if checked: