diff --git a/tianshou/highlevel/params/policy_params.py b/tianshou/highlevel/params/policy_params.py
index 7bf5ef4..540eec9 100644
--- a/tianshou/highlevel/params/policy_params.py
+++ b/tianshou/highlevel/params/policy_params.py
@@ -189,36 +189,27 @@ class ParamTransformerAutoAlpha(ParamTransformer):
             kwargs[self.key] = alpha.create_auto_alpha(data.envs, data.optim_factory, data.device)
 
 
-class ParamTransformerNoiseFactory(ParamTransformer):
-    def __init__(self, key: str):
-        self.key = key
-
-    def transform(self, params: dict[str, Any], data: ParamTransformerData) -> None:
-        value = params[self.key]
+class ParamTransformerNoiseFactory(ParamTransformerChangeValue):
+    def change_value(self, value: Any, data: ParamTransformerData) -> Any:
         if isinstance(value, NoiseFactory):
-            params[self.key] = value.create_noise(data.envs)
+            value = value.create_noise(data.envs)
+        return value
 
 
-class ParamTransformerFloatEnvParamFactory(ParamTransformer):
-    def __init__(self, key: str):
-        self.key = key
-
-    def transform(self, kwargs: dict[str, Any], data: ParamTransformerData) -> None:
-        value = kwargs[self.key]
+class ParamTransformerFloatEnvParamFactory(ParamTransformerChangeValue):
+    def change_value(self, value: Any, data: ParamTransformerData) -> Any:
         if isinstance(value, EnvValueFactory):
-            kwargs[self.key] = value.create_value(data.envs)
+            value = value.create_value(data.envs)
+        return value
 
 
-class ParamTransformerDistributionFunction(ParamTransformer):
-    def __init__(self, key: str):
-        self.key = key
-
-    def transform(self, kwargs: dict[str, Any], data: ParamTransformerData) -> None:
-        value = kwargs[self.key]
+class ParamTransformerDistributionFunction(ParamTransformerChangeValue):
+    def change_value(self, value: Any, data: ParamTransformerData) -> Any:
         if value == "default":
-            kwargs[self.key] = DistributionFunctionFactoryDefault().create_dist_fn(data.envs)
+            value = DistributionFunctionFactoryDefault().create_dist_fn(data.envs)
         elif isinstance(value, DistributionFunctionFactory):
-            kwargs[self.key] = value.create_dist_fn(data.envs)
+            value = value.create_dist_fn(data.envs)
+        return value
 
 
 class ParamTransformerActionScaling(ParamTransformerChangeValue):