[HELP .NET]

I immediately inform you that I do not know about coding.
I have something like:

Code:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <configSections>
        <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
            <section name="app_name.My.MySettings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
        </sectionGroup>
    </configSections>
    <userSettings>
        <app_name.My.MySettings>
            <setting name="register" serializeAs="String">
                <value />
            </setting>
        </app_name.My.MySettings>
    </userSettings>
</configuration>

The program shows the message. I would like him not to show it. When I modify the value of PublicKeyToken to a different value, the program throws the error but it continues to work.