diff --git a/banking_breakdown/ui/main_window.py b/banking_breakdown/ui/main_window.py
index 2db10b8..b55974f 100644
--- a/banking_breakdown/ui/main_window.py
+++ b/banking_breakdown/ui/main_window.py
@@ -41,11 +41,10 @@ class MainWindow(QMainWindow):
         # Set up QTableView model
 
         self._pandas_model = PandasModel(self)
-        self._proxyModel = QSortFilterProxyModel(self)
-        self._proxyModel.setSourceModel(self._pandas_model)
-        self._table_view.setModel(self._proxyModel)
-        self._proxyModel.setDynamicSortFilter(True)
-        self._proxyModel.setSortRole(Qt.ItemDataRole.EditRole)
+        self._proxy_model = QSortFilterProxyModel(self)
+        self._proxy_model.setSourceModel(self._pandas_model)
+        self._table_view.setModel(self._proxy_model)
+        self._proxy_model.setSortRole(Qt.ItemDataRole.EditRole)
 
         # Set event handlers
 
@@ -61,6 +60,7 @@ class MainWindow(QMainWindow):
         header.setContextMenuPolicy(Qt.ContextMenuPolicy.CustomContextMenu)
         header.customContextMenuRequested.connect(
             self._handle_header_right_click)
+        header.sectionClicked.connect(self._handle_header_left_click)
 
         self._list_widget.itemSelectionChanged.connect(
             self._handle_list_selection_changed)
@@ -110,6 +110,9 @@ class MainWindow(QMainWindow):
     def _update_categories_from_dataframe(self):
         df = self._pandas_model.get_dataframe()
 
+        if 'category' not in df.columns:
+            df['category'] = [' '] * len(df.index)
+
         df_categories = df['category'].unique()
         current_categories = [self._list_widget.item(x).text() for x
                               in range(self._list_widget.count())]
@@ -154,6 +157,11 @@ class MainWindow(QMainWindow):
     # Event handlers
     #
 
+    def _handle_header_left_click(self, logical_index):
+        self._proxy_model.sort(logical_index,
+                               self._table_view.horizontalHeader()
+                               .sortIndicatorOrder())
+
     def _handle_header_right_click(self, pos):
         column = self._table_view.horizontalHeader().logicalIndexAt(pos)
 
@@ -185,10 +193,15 @@ class MainWindow(QMainWindow):
                                       f"Are you sure you want to delete"
                                       f" category '{selected_item.text()}'?")
 
+        df = self._pandas_model.get_dataframe()
+
+        if 'category' not in df.columns:
+            df['category'] = [' '] * len(df.index)
+
         if button == QMessageBox.StandardButton.Yes:
-            self._list_widget.takeItem(self._list_widget.row(selected_item))
-            df = self.get_statement_data()
             df.loc[df['category'] == selected_item.text(), 'category'] = ' '
+            self._list_widget.takeItem(self._list_widget.row(selected_item))
+            self._pandas_model.set_dataframe(df)
 
     def _handle_clear_click(self):
         self._assign_category(' ')
@@ -201,7 +214,6 @@ class MainWindow(QMainWindow):
 
         df = self._pandas_model.get_dataframe()
         df.loc[row_indices, 'category'] = category
-
         self._pandas_model.set_dataframe(df)
 
     def _handle_apply_click(self):
diff --git a/banking_breakdown/ui/pandas_model.py b/banking_breakdown/ui/pandas_model.py
index 9d703c1..f8371bf 100644
--- a/banking_breakdown/ui/pandas_model.py
+++ b/banking_breakdown/ui/pandas_model.py
@@ -1,7 +1,7 @@
 import numpy
 import pandas as pd
 from PyQt6 import QtCore
-from PyQt6.QtCore import Qt, QModelIndex
+from PyQt6.QtCore import Qt, QModelIndex, QSortFilterProxyModel
 
 
 def _get_str_dataframe(df: pd.DataFrame) -> pd.DataFrame:
diff --git a/res/main_window.ui b/res/main_window.ui
index d6a7858..2a2b799 100644
--- a/res/main_window.ui
+++ b/res/main_window.ui
@@ -127,8 +127,11 @@
             <enum>QAbstractItemView::SelectRows</enum>
            </property>
            <property name="sortingEnabled">
-            <bool>true</bool>
+            <bool>false</bool>
            </property>
+           <attribute name="horizontalHeaderShowSortIndicator" stdset="0">
+            <bool>true</bool>
+           </attribute>
            <attribute name="horizontalHeaderStretchLastSection">
             <bool>true</bool>
            </attribute>