checkbox is getting clicked cheked/ unchecked everywhere

I want to check / unchecked this checkbox name fbox3 nspan when user click on it but it is also gets check / unchecked on clicked on label "Send a welcome email with login details to the user." also on above button "Save & Continue" i want to check / unchecked checkbox only on clicking on checkbox fbox3 nspan only . what i need to do ??

  <div class="fbox6">
                                    <form:label path="securityPin">PIN</form:label>
                                    <form:input path="securityPin" disabled="${!authorizedUser}" maxlength="4" ></form:input>
                                </div>
                                <span id="user.securityPin" class="valerror"></span>
                                <br clear="all" />
                                <div class="fbox3 nspan">
                                    <form:checkbox path="sendWelcomeEmail"  cssClass="label-revert" checked="true"
                                        label="Send a welcome email with login details to the user." />
                                </div>
                                <div id="bttn_save_user" class="bttns bttnsfbox">
                                    <input type="button" class="bttn save" value="Save & Continue" onclick="createUser()"/>
                                </div>
                            </form:form>