diff --git a/widgets/AddCustomInstructionDialog.cpp b/widgets/AddCustomInstructionDialog.cpp
index 1aba178..ac9e076 100644
--- a/widgets/AddCustomInstructionDialog.cpp
+++ b/widgets/AddCustomInstructionDialog.cpp
@@ -20,6 +20,7 @@
 #include "AddCustomInstructionDialog.hpp"
 #include "QodeAssisttr.h"
 
+#include <QCheckBox>
 #include <QDialogButtonBox>
 #include <QFormLayout>
 #include <QLabel>
@@ -46,6 +47,7 @@ AddCustomInstructionDialog::AddCustomInstructionDialog(const CustomInstruction &
     setupUi();
     m_nameEdit->setText(instruction.name);
     m_bodyEdit->setPlainText(instruction.body);
+    m_defaultCheckBox->setChecked(instruction.isDefault);
     resize(500, 400);
 }
 
@@ -70,6 +72,11 @@ void AddCustomInstructionDialog::setupUi()
         Tr::tr("Enter the refactoring instruction that will be sent to the LLM..."));
     mainLayout->addWidget(m_bodyEdit);
 
+    m_defaultCheckBox = new QCheckBox(Tr::tr("Set as default instruction"), this);
+    m_defaultCheckBox->setToolTip(
+        Tr::tr("This instruction will be automatically selected when opening Quick Refactor dialog"));
+    mainLayout->addWidget(m_defaultCheckBox);
+
     QDialogButtonBox *buttonBox
         = new QDialogButtonBox(QDialogButtonBox::Save | QDialogButtonBox::Cancel, this);
 
@@ -95,6 +102,7 @@ CustomInstruction AddCustomInstructionDialog::getInstruction() const
     CustomInstruction instruction = m_instruction;
     instruction.name = m_nameEdit->text().trimmed();
     instruction.body = m_bodyEdit->toPlainText().trimmed();
+    instruction.isDefault = m_defaultCheckBox->isChecked();
     return instruction;
 }
 
diff --git a/widgets/AddCustomInstructionDialog.hpp b/widgets/AddCustomInstructionDialog.hpp
index fc3968b..fd0224c 100644
--- a/widgets/AddCustomInstructionDialog.hpp
+++ b/widgets/AddCustomInstructionDialog.hpp
@@ -26,6 +26,7 @@
 
 class QLineEdit;
 class QPlainTextEdit;
+class QCheckBox;
 
 namespace QodeAssist {
 
@@ -45,6 +46,7 @@ private:
     
     QLineEdit *m_nameEdit;
     QPlainTextEdit *m_bodyEdit;
+    QCheckBox *m_defaultCheckBox;
     CustomInstruction m_instruction;
 };
 
diff --git a/widgets/CustomInstructionsManager.cpp b/widgets/CustomInstructionsManager.cpp
index 93fb3b6..552e4d7 100644
--- a/widgets/CustomInstructionsManager.cpp
+++ b/widgets/CustomInstructionsManager.cpp
@@ -93,6 +93,7 @@ bool CustomInstructionsManager::loadInstructions()
         instruction.id = obj["id"].toString();
         instruction.name = obj["name"].toString();
         instruction.body = obj["body"].toString();
+        instruction.isDefault = obj["default"].toBool(false);
 
         if (instruction.id.isEmpty() || instruction.name.isEmpty()) {
             LOG_MESSAGE(QString("Invalid instruction in file: %1").arg(fileInfo.fileName()));
@@ -132,6 +133,33 @@ bool CustomInstructionsManager::saveInstruction(const CustomInstruction &instruc
         }
     }
 
+    // If this instruction is marked as default, remove default flag from all others
+    if (newInstruction.isDefault) {
+        for (int i = 0; i < m_instructions.size(); ++i) {
+            if (m_instructions[i].id != newInstruction.id && m_instructions[i].isDefault) {
+                m_instructions[i].isDefault = false;
+                
+                // Update the file for this instruction
+                QString sanitizedName = m_instructions[i].name;
+                sanitizedName.replace(' ', '_');
+                QString otherFileName = QString("%1/%2_%3.json")
+                    .arg(getInstructionsDirectory(), sanitizedName, m_instructions[i].id);
+                
+                QJsonObject otherObj;
+                otherObj["id"] = m_instructions[i].id;
+                otherObj["name"] = m_instructions[i].name;
+                otherObj["body"] = m_instructions[i].body;
+                otherObj["default"] = false;
+                otherObj["version"] = "0.1";
+                
+                QFile otherFile(otherFileName);
+                if (otherFile.open(QIODevice::WriteOnly)) {
+                    otherFile.write(QJsonDocument(otherObj).toJson(QJsonDocument::Indented));
+                }
+            }
+        }
+    }
+
     int existingIndex = -1;
     for (int i = 0; i < m_instructions.size(); ++i) {
         if (m_instructions[i].id == newInstruction.id) {
@@ -144,6 +172,7 @@ bool CustomInstructionsManager::saveInstruction(const CustomInstruction &instruc
     obj["id"] = newInstruction.id;
     obj["name"] = newInstruction.name;
     obj["body"] = newInstruction.body;
+    obj["default"] = newInstruction.isDefault;
     obj["version"] = "0.1";
 
     QJsonDocument doc(obj);
diff --git a/widgets/CustomInstructionsManager.hpp b/widgets/CustomInstructionsManager.hpp
index b08432c..1a99305 100644
--- a/widgets/CustomInstructionsManager.hpp
+++ b/widgets/CustomInstructionsManager.hpp
@@ -30,6 +30,7 @@ struct CustomInstruction
     QString id;
     QString name;
     QString body;
+    bool isDefault = false;
 };
 
 class CustomInstructionsManager : public QObject
diff --git a/widgets/QuickRefactorDialog.cpp b/widgets/QuickRefactorDialog.cpp
index b2180be..6ef490d 100644
--- a/widgets/QuickRefactorDialog.cpp
+++ b/widgets/QuickRefactorDialog.cpp
@@ -320,9 +320,16 @@ void QuickRefactorDialog::loadCustomCommands()
     const QVector<CustomInstruction> &instructions = manager.instructions();
 
     QStringList instructionNames;
-    for (const CustomInstruction &instruction : instructions) {
+    int defaultInstructionIndex = -1;
+    
+    for (int i = 0; i < instructions.size(); ++i) {
+        const CustomInstruction &instruction = instructions[i];
         m_commandsComboBox->addItem(instruction.name, instruction.id);
         instructionNames.append(instruction.name);
+        
+        if (instruction.isDefault) {
+            defaultInstructionIndex = i + 1;
+        }
     }
 
     if (m_commandsComboBox->completer()) {
@@ -330,6 +337,10 @@ void QuickRefactorDialog::loadCustomCommands()
         m_commandsComboBox->completer()->setModel(model);
     }
 
+    if (defaultInstructionIndex > 0) {
+        m_commandsComboBox->setCurrentIndex(defaultInstructionIndex);
+    }
+
     bool hasInstructions = !instructions.isEmpty();
     m_editCommandButton->setEnabled(hasInstructions);
     m_deleteCommandButton->setEnabled(hasInstructions);