[EDIT] URLパターンを変更しました。

src/main/java/com/example/demo/app/domain/service/impl/UserServiceImpl.java

@@ -45,13 +45,11 @@ public class UserServiceImpl implements UserService {
 		GoalEntity goalEntity = new GoalEntity();
 		goalEntity.setTargetAmount(Integer.parseInt(String.valueOf(userForm.getGoalId())));
 
-		goalRepository.save(
-				goalEntity);
-
 		CourseEntity courseEntity = courseRepository.findById(courseId).orElse(null);
 
 		userEntity.setQuestionEntity(questionEntity);
-		userEntity.setGoalEntity(goalEntity);
+		userEntity.setGoalEntity(goalRepository.save(
+				goalEntity));
 		userEntity.setCourseEntity(courseEntity);
 
 		userEntity.setDeleteFlag(0);

src/main/java/com/example/demo/app/presentation/controller/CourseController.java

@@ -1,8 +1,5 @@
 package com.example.demo.app.presentation.controller;
 
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
 import jakarta.servlet.http.HttpSession;
 
 import org.springframework.stereotype.Controller;
@@ -25,74 +22,53 @@ import lombok.RequiredArgsConstructor;
 
 
 @Controller
-//@RequestMapping("/course")
 @RequiredArgsConstructor
 public class CourseController {
 
-	private final static Logger LOGGER = Logger.getLogger(CourseController.class.getName());
-    // エラーメッセージ用の定数フィールド
-    private final static String SEVERE_ERROR_MESSAGE = "エラーが発生しました！";
-
-    private final HttpSession httpSession;
     private final CourseService courseService;
     private final CourseInfoService courseInfoService;
     private final UserService userService;
     
     
-    @PostMapping("/course/select/register")
+    @PostMapping("/user/register/course")
     public String showSelectCourse(@ModelAttribute UserForm userForm, Model model, HttpSession session) {
     	
-    	try {
-    		
-    		session.setAttribute("userForm", userForm);
-    		model.addAttribute("mode", "regist");
-    		model.addAttribute("courseList", CourseForm.convertFrom(courseService.findAll()));
-    		model.addAttribute("courseInfoList", CourseInfoForm.convertFrom(courseInfoService.findAll()));
     	
     		
-    		return "select_course";
+		session.setAttribute("userForm", userForm);
+		model.addAttribute("mode", "regist");
+		model.addAttribute("currentCourseId", 4);
+		model.addAttribute("courseList", CourseForm.convertFrom(courseService.findAll()));
+		model.addAttribute("courseInfoList", CourseInfoForm.convertFrom(courseInfoService.findAll()));
   
-    	} catch (Exception e) {
-    		// ログイン情報の破棄
-            httpSession.invalidate();
+    	return "select_course";
     		
-            e.printStackTrace();
     	
-            // エラーログ出力
-            LOGGER.log(Level.SEVERE, SEVERE_ERROR_MESSAGE, e);
-            // エラー画面遷移
-            return null;
-    	}
     }
     
     @SessionCheck
-    @GetMapping("/select/change")
-    public String showChangeCourse(Model model) {
+    @GetMapping("/course")
+    public String showChangeCourse(Model model, HttpSession session) {
     	
-    	try {
     	
-    		model.addAttribute("mode", "change");
-    		model.addAttribute("courseList", CourseForm.convertFrom(courseService.findAll()));
-    		model.addAttribute("courseInfoList", CourseInfoForm.convertFrom(courseInfoService.findAll()));
+		LoginModel loginUser = (LoginModel) session.getAttribute("loginUser");
+		Long userId = loginUser.getUserId();
 		
-    		return "select_course";
+		Long currentCourseId = userService.findByUserId(userId).getCourseId();
+		model.addAttribute("mode", "change");
+		model.addAttribute("currentCourseId", currentCourseId);
+		model.addAttribute("courseList", CourseForm.convertFrom(courseService.findAll()));
+		model.addAttribute("courseInfoList", CourseInfoForm.convertFrom(courseInfoService.findAll()));
 		
-    	} catch (Exception e) {
-    		// ログイン情報の破棄
-            httpSession.invalidate();
 
-            e.printStackTrace();
+		return "select_course";
+    		
     	
-            // エラーログ出力
-            LOGGER.log(Level.SEVERE, SEVERE_ERROR_MESSAGE, e);
-            // エラー画面遷移
-            return null;
-    	}
     }
     
     @SessionCheck
     @PostMapping("/change")
-    public String changeCourse(@RequestParam Long courseId) {
+    public String changeCourse(@RequestParam Long courseId, HttpSession httpSession) {
     	
     	LoginModel loginUser = (LoginModel) httpSession.getAttribute("loginUser");
 

src/main/resources/templates/select_course.html

@@ -7,6 +7,7 @@
 <title>コース選択</title>
 </head>
 <body>
+	<div th:replace="~{header :: header}"></div>
 	
 	<h1>コース選択</h1>
 	
@@ -17,7 +18,7 @@
 		<div class="accordion" id="accordionExample">
 		  <div class="accordion-item" th:each="course:${courseList}">
 		    <h2 class="accordion-header d-flex align-items-center">
-			  <input type="radio" name="courseId" th:value="${course.courseId}" class="form-check-input ms-3 me-2">
+			  <input type="radio" name="courseId" th:value="${course.courseId}" th:checked="${course.courseId==currentCourseId}" class="form-check-input ms-3 me-2">
 		      <button class="accordion-button collapsed" type="button" data-bs-toggle="collapse" th:data-bs-target="'#collapse' + ${course.courseId}" aria-expanded="false" aria-controls="'collapse' + ${course.courseId}">
 				<span th:text="${course.courseName}"></span>
 		      </button>

src/main/resources/templates/user_register.html

@@ -13,7 +13,7 @@
 	<main>
 		<h1>新規会員登録</h1>
 		
-		<form th:action="@{/course/select/register}" th:object="${userForm}" method="post">
+		<form th:action="@{/user/register/course}" th:object="${userForm}" method="post">
 			<div>
 				<label for="userName">氏名</label>
 				<input type="text"