diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8bddac0..e822d2f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+1.6.3
+
+<!-- - abort :: add checkbox to prevent from loading project environnement namespace -->
+- add buttons to load manually environnement namespace
+
 1.6.2
 
 - disable keymap register for breakdowner on background
diff --git a/__init__.py b/__init__.py
index a036201..7c27027 100755
--- a/__init__.py
+++ b/__init__.py
@@ -15,7 +15,7 @@ bl_info = {
 "name": "GP toolbox",
 "description": "Set of tools for Grease Pencil in animation production",
 "author": "Samuel Bernou, Christophe Seux",
-"version": (1, 6, 2),
+"version": (1, 6, 3),
 "blender": (2, 91, 0),
 "location": "Sidebar (N menu) > Gpencil > Toolbox / Gpencil properties",
 "warning": "",
@@ -195,6 +195,7 @@ class GPTB_prefs(bpy.types.AddonPreferences):
         description="Path to brushes containing the blends holding the brushes",
         default="//", maxlen=0, subtype='DIR_PATH')#, update = set_palette_path
 
+    ## namespace
     separator : StringProperty(
         name="Separator",
         description="Character delimiter to use for detecting namespace (prefix), default is '_', space if nothing specified",
@@ -210,6 +211,12 @@ class GPTB_prefs(bpy.types.AddonPreferences):
         description="List of suffixes (two capital letters) available for layers(ex: OL,UL)",
         default="", maxlen=0)
 
+    # use_env_namespace : BoolProperty(
+    #     name="Use Project namespace",
+    #     description="Ovewrite prefix/suffix with Project values defined in environnement at startup\n(key 'PREFIXES and SUFFIXES')",
+    #     default=True,
+    #     )
+
     show_prefix_buttons : BoolProperty(
         name="Show Prefix Buttons",
         description="Show prefix and suffix buttons above layer stack",
@@ -343,14 +350,19 @@ class GPTB_prefs(bpy.types.AddonPreferences):
             ## render output
             subbox.prop(self, 'output_path')
 
-            ## render output
+            ## namespace
             subbox = box.box()
             subbox.label(text='Namespace:')
             subbox.prop(self, 'separator')
             subbox.prop(self, 'show_prefix_buttons', text='Use Prefixes Toggles')
             if self.show_prefix_buttons:
-                subbox.prop(self, 'prefixes')
-                subbox.prop(self, 'suffixes')
+                # subbox.prop(self, 'use_env_namespace')
+                row = subbox.row()
+                row.prop(self, 'prefixes')
+                row.operator('prefs.reset_gp_toolbox_env', text='', icon='LOOP_BACK').mode = 'PREFIXES'
+                row = subbox.row()
+                row.prop(self, 'suffixes')
+                row.operator('prefs.reset_gp_toolbox_env', text='', icon='LOOP_BACK').mode = 'SUFFIXES'
 
             ### TODO add render settings
 
@@ -488,6 +500,7 @@ def set_env_properties():
     if prefs.use_env_brushes:
         prefs.brush_path = brushes if brushes else prefs.brush_path
 
+    # if prefs.use_env_namespace:
     prefix_list = os.getenv('PREFIXES')
     prefs.prefixes = prefix_list if prefix_list else prefs.prefixes
     
@@ -497,6 +510,34 @@ def set_env_properties():
     separator = os.getenv('SEPARATOR')
     prefs.separator = separator if separator else prefs.separator
 
+
+class GPTB_set_env_settings(bpy.types.Operator):
+    """manually reset prefs from project environnement setttings"""
+    bl_idname = "prefs.reset_gp_toolbox_env"
+    bl_label = "Reset prefs from project environnement settings (if any)"
+
+    mode : bpy.props.StringProperty(default='ALL', options={'SKIP_SAVE'}) # 'HIDDEN', 
+
+    def execute(self, context):
+        prefs = get_addon_prefs()
+        if self.mode == 'ALL':
+            set_env_properties()
+        elif self.mode == 'PREFIXES':
+            prefix_list = os.getenv('PREFIXES')
+            if not prefix_list:
+                self.report({'ERROR'}, 'No prefix preset to load from project environnement')
+                return {'CANCELLED'}
+            prefs.prefixes = prefix_list if prefix_list else prefs.prefixes
+        
+        elif self.mode == 'SUFFIXES':
+            suffix_list = os.getenv('SUFFIXES')
+            if not suffix_list:
+                self.report({'ERROR'}, 'No suffix preset to load from project environnement')
+                return {'CANCELLED'}
+            prefs.suffixes = suffix_list if suffix_list else prefs.suffixes
+        return {'FINISHED'}
+
+
 ### --- REGISTER ---
 
 # class GP_PG_ToolsSettings(bpy.types.PropertyGroup) :
@@ -506,6 +547,7 @@ def set_env_properties():
 classes = (
 GP_PG_FixSettings,
 GP_PG_ToolsSettings,
+GPTB_set_env_settings,
 GPTB_prefs,
 GPT_OT_auto_tint_gp_layers,
 )