diff --git a/apps/gui/main.cpp b/apps/gui/main.cpp
index 30d4518..ac857bf 100644
--- a/apps/gui/main.cpp
+++ b/apps/gui/main.cpp
@@ -131,6 +131,16 @@ int main(int argc, char ** argv)
                     if (b->text() == QObject::tr("确定")) { b->click(); break; }
                 }
             }
+            else if (autoclose == QLatin1String("apply")) {               // 点「应用」，应保持打开
+                for (auto * b : dlg.findChildren<QPushButton *>()) {
+                    if (b->text() == QObject::tr("应用")) { b->click(); break; }
+                }
+                QTimer::singleShot(400, &dlg, [&dlg] {
+                    std::fprintf(stderr, "点「应用」后对话框仍可见: %s\n",
+                                 dlg.isVisible() ? "是 ✅" : "否 ❌");
+                    dlg.reject();
+                });
+            }
         });
     };
 
@@ -197,17 +207,35 @@ int main(int argc, char ** argv)
         qWarning("采集失败: %s", qUtf8Printable(m));
     });
 
-    // 语言 pill → 设置
-    QObject::connect(&window, &lc::CaptionWindow::languageClicked, &window, [&] {
+    // 后端相关项（模型/语言/采集设备）变化才需要重启；外观类改动即时生效
+    const auto backendKey = [&cfg] {
+        return cfg.modelId + QLatin1Char('|') + cfg.language + QLatin1Char('|') + cfg.captureDevice;
+    };
+    QString activeKey = backendKey();
+
+    const auto openSettings = [&] {
         lc::SettingsDialog dlg(false);
+        QObject::connect(&dlg, &lc::SettingsDialog::settingsApplied, &window, [&] {
+            applyAppearance(window, cfg);          // 透明度/字号等立刻可见
+            if (backendKey() != activeKey) {
+                if (startTranscriber()) activeKey = backendKey();
+            }
+        });
         if (dlg.exec() == QDialog::Accepted) {
             applyAppearance(window, cfg);
-            if (!startTranscriber()) {
-                QMessageBox::warning(&window, QObject::tr("启动失败"),
-                                     QObject::tr("模型加载失败，请检查设置。"));
+            if (backendKey() != activeKey) {
+                if (!startTranscriber()) {
+                    QMessageBox::warning(&window, QObject::tr("启动失败"),
+                                         QObject::tr("模型加载失败，请检查设置。"));
+                } else {
+                    activeKey = backendKey();
+                }
             }
         }
-    });
+    };
+
+    // 语言 pill → 设置
+    QObject::connect(&window, &lc::CaptionWindow::languageClicked, &window, openSettings);
 
     // ---- 托盘 ----
     QSystemTrayIcon * tray = nullptr;
@@ -224,13 +252,7 @@ int main(int argc, char ** argv)
 
         QObject::connect(showAct, &QAction::triggered, &window,
                          [&window] { window.setVisible(!window.isVisible()); });
-        QObject::connect(setAct, &QAction::triggered, &window, [&] {
-            lc::SettingsDialog dlg(false);
-            if (dlg.exec() == QDialog::Accepted) {
-                applyAppearance(window, cfg);
-                startTranscriber();
-            }
-        });
+        QObject::connect(setAct, &QAction::triggered, &window, openSettings);
         QObject::connect(quitAct, &QAction::triggered, &app, &QApplication::quit);
         QObject::connect(tray, &QSystemTrayIcon::activated, &window,
                          [&window](QSystemTrayIcon::ActivationReason r) {
diff --git a/docs/asr-backends.md b/docs/asr-backends.md
index 04c7c9d..c0678f9 100644
--- a/docs/asr-backends.md
+++ b/docs/asr-backends.md
@@ -63,6 +63,16 @@ IAsr（src/core/iasr.h）
 > 同步/自旋开销会让它更慢（8 线程比 1 线程慢 2.6 倍、CPU 高 28 倍）。所以适配器里固定
 > `threads = 1`。
 
+## 设置对话框
+
+三个页签（模型 / 显示 / 高级），底部三个按钮：
+
+- **应用**：应用设置但**不关闭**对话框，方便实时预览（改不透明度、字号时会立刻看到效果）；
+- **取消**：放弃本次改动；
+- **确定**：应用并关闭。
+
+只有**模型 / 识别语言 / 采集设备**变化才会重启识别后端；透明度、字号、行数、位置这类外观改动是即时生效的，不会打断正在进行的转写。
+
 ## 采集设备选择
 
 默认跟随系统默认输出；也可以在设置里指定某个输出设备（`--list-devices` 可列出）：
diff --git a/src/ui/settingsdialog.cpp b/src/ui/settingsdialog.cpp
index 6de4ef3..10ec1d4 100644
--- a/src/ui/settingsdialog.cpp
+++ b/src/ui/settingsdialog.cpp
@@ -54,15 +54,18 @@ SettingsDialog::SettingsDialog(bool firstRun, QWidget * parent)
                            : QString());
 
     auto * okBtn     = new QPushButton(tr("确定"), this);
+    auto * applyBtn  = new QPushButton(tr("应用"), this);
     auto * cancelBtn = new QPushButton(tr("取消"), this);
     okBtn->setDefault(true);
-    connect(okBtn, &QPushButton::clicked, this, [this] {
-        if (ensureModelSelected()) onApply();
-    });
+    okBtn->setToolTip(tr("应用并关闭"));
+    applyBtn->setToolTip(tr("应用但不关闭，方便预览效果"));
+    connect(okBtn,     &QPushButton::clicked, this, &SettingsDialog::onAccept);
+    connect(applyBtn,  &QPushButton::clicked, this, &SettingsDialog::onApplyClicked);
     connect(cancelBtn, &QPushButton::clicked, this, &QDialog::reject);
 
     auto * buttons = new QHBoxLayout;
     buttons->addStretch(1);
+    buttons->addWidget(applyBtn);
     buttons->addWidget(cancelBtn);
     buttons->addWidget(okBtn);
 
@@ -440,7 +443,20 @@ bool SettingsDialog::ensureModelSelected()
     return true;
 }
 
-void SettingsDialog::onApply()
+void SettingsDialog::onAccept()
+{
+    if (ensureModelSelected()) {
+        applySettings();
+        accept();
+    }
+}
+
+void SettingsDialog::onApplyClicked()
+{
+    if (ensureModelSelected()) applySettings();
+}
+
+void SettingsDialog::applySettings()
 {
     AppSettings & cfg = AppSettings::instance();
     cfg.mirrorBase = mirrorEdit_->text().trimmed();
@@ -469,7 +485,6 @@ void SettingsDialog::onApply()
     }
     cfg.save();
     Q_EMIT settingsApplied();
-    accept();
 }
 
 } // namespace lc
diff --git a/src/ui/settingsdialog.h b/src/ui/settingsdialog.h
index 3ddff85..79ce810 100644
--- a/src/ui/settingsdialog.h
+++ b/src/ui/settingsdialog.h
@@ -41,7 +41,9 @@ private:
     void onVerify();
     void onDelete();
     void onOpenDir();
-    void onApply();
+    void applySettings();   // 读取控件 → 保存 → 发 settingsApplied（不关闭对话框）
+    void onAccept();        // 确定：applySettings + 关闭
+    void onApplyClicked();  // 应用：只 applySettings
     bool ensureModelSelected();
 
     QTableWidget * table_      = nullptr;