diff --git a/src/Gui/Application.cpp b/src/Gui/Application.cpp
index 7acd57933f..8f46494588 100644
--- a/src/Gui/Application.cpp
+++ b/src/Gui/Application.cpp
@@ -141,6 +141,7 @@
 #include "QtWidgets.h"
 
 #include <OverlayManager.h>
+#include <ParamHandler.h>
 #include <Base/ServiceProvider.h>
 
 #ifdef BUILD_TRACY_FRAME_PROFILER
@@ -381,20 +382,48 @@ struct PyMethodDef FreeCADGui_methods[] = {
 
 void Application::initStyleParameterManager()
 {
+    static ParamHandlers handlers;
+
+    const auto deduceParametersFilePath = []() -> std::string {
+        const auto hMainWindowGrp = App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/MainWindow");
+
+        if (const std::string& path = hMainWindowGrp->GetASCII("ThemeStyleParametersFile");
+            !path.empty()) {
+            return path;
+        }
+
+        return fmt::format("qss:parameters/{}.yaml", hMainWindowGrp->GetASCII("Theme", "Classic"));
+    };
+
+    auto themeParametersSource = new StyleParameters::YamlParameterSource(
+        deduceParametersFilePath(),
+        {.name = QT_TR_NOOP("Theme Parameters"),
+         .options = StyleParameters::ParameterSourceOption::UserEditable});
+
+    handlers.addDelayedHandler(
+        "BaseApp/Preferences/MainWindow",
+        {"ThemeStyleParametersFiles", "Theme"},
+        [themeParametersSource, deduceParametersFilePath](ParameterGrp::handle) {
+            themeParametersSource->changeFilePath(deduceParametersFilePath());
+        });
+
     Base::registerServiceImplementation<StyleParameters::ParameterSource>(
         new StyleParameters::BuiltInParameterSource({.name = QT_TR_NOOP("Built-in Parameters")}));
 
-    Base::registerServiceImplementation<StyleParameters::ParameterSource>(
-        new StyleParameters::UserParameterSource(
-            App::GetApplication().GetParameterGroupByPath(
-                "User parameter:BaseApp/Preferences/Themes/Tokens"),
-            {.name = QT_TR_NOOP("Theme Parameters"),
-             .options = StyleParameters::ParameterSourceOption::UserEditable}));
-
+    // todo: left for compatibility with older theme versions, to be removed before release
     Base::registerServiceImplementation<StyleParameters::ParameterSource>(
         new StyleParameters::UserParameterSource(
             App::GetApplication().GetParameterGroupByPath(
                 "User parameter:BaseApp/Preferences/Themes/UserTokens"),
+            {.name = QT_TR_NOOP("Theme Parameters - Fallback"),
+             .options = StyleParameters::ParameterSourceOption::ReadOnly}));
+
+    Base::registerServiceImplementation<StyleParameters::ParameterSource>(themeParametersSource);
+
+    Base::registerServiceImplementation<StyleParameters::ParameterSource>(
+        new StyleParameters::UserParameterSource(
+            App::GetApplication().GetParameterGroupByPath(
+                "User parameter:BaseApp/Preferences/Themes/UserParameters"),
             {.name = QT_TR_NOOP("User Parameters"),
              .options = StyleParameters::ParameterSource::UserEditable}));
 
diff --git a/src/Gui/StyleParameters/ParameterManager.cpp b/src/Gui/StyleParameters/ParameterManager.cpp
index 8fa1727609..9aa9894eaf 100644
--- a/src/Gui/StyleParameters/ParameterManager.cpp
+++ b/src/Gui/StyleParameters/ParameterManager.cpp
@@ -223,7 +223,17 @@ void UserParameterSource::remove(const std::string& name)
 
 YamlParameterSource::YamlParameterSource(const std::string& filePath, const Metadata& metadata)
     : ParameterSource(metadata)
-    , filePath(filePath)
+{
+    changeFilePath(filePath);
+}
+
+void YamlParameterSource::changeFilePath(const std::string& path)
+{
+    this->filePath = path;
+    reload();
+}
+
+void YamlParameterSource::reload()
 {
     QFile file(QString::fromStdString(filePath));
 
@@ -240,6 +250,7 @@ YamlParameterSource::YamlParameterSource(const std::string& filePath, const Meta
     std::string content = in.readAll().toStdString();
 
     YAML::Node root = YAML::Load(content);
+    parameters.clear();
     for (auto it = root.begin(); it != root.end(); ++it) {
         auto key = it->first.as<std::string>();
         auto value = it->second.as<std::string>();
@@ -288,7 +299,7 @@ void YamlParameterSource::flush()
 
     QFile file(QString::fromStdString(filePath));
     if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate | QIODevice::Text)) {
-        FC_TRACE("StyleParameters: Unable to open file " << filePath);
+        FC_WARN("StyleParameters: Unable to open file " << filePath);
         return;
     }
 
diff --git a/src/Gui/StyleParameters/ParameterManager.h b/src/Gui/StyleParameters/ParameterManager.h
index a2832a9030..fb13994494 100644
--- a/src/Gui/StyleParameters/ParameterManager.h
+++ b/src/Gui/StyleParameters/ParameterManager.h
@@ -403,6 +403,9 @@ public:
      */
     explicit YamlParameterSource(const std::string& filePath, const Metadata& metadata = {});
 
+    void changeFilePath(const std::string& path);
+    void reload();
+
     std::list<Parameter> all() const override;
     std::optional<Parameter> get(const std::string& name) const override;
     void define(const Parameter& param) override;