Design pattern for retrofit interface

I have trouble with the design of my Retrofit interface creator. I want to be able to instanciate the API interface in a generic way and update the corresponding instance whenever a token is passed. Currently, when I update the token, I have to call createService() method again to get the new instance that used the token in the generation of the Interface...

Somebody asked for a similar question but never got an answer here

public class RetrofitCreator {

    private static String TAG = "RetrofitCreator";
    private static String WSSE = null;
    private static String AmzToken = null;
    static HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
    private static AmazonAPI amazonAPI = null;
    private static VanishAPI cobaltAPI = null;

    //static OkHttpClient client = new OkHttpClient.Builder().build();
    static OkHttpClient.Builder httpClient = new OkHttpClient.Builder().addInterceptor(interceptor.setLevel(HttpLoggingInterceptor.Level.BODY));

    private static Retrofit.Builder builder =
            new Retrofit.Builder();

    public static <S> S createService(Class<S> serviceClass) {

        S mAPI = null;
            if(serviceClass.getSimpleName().equals("VanishAPI")){
                if(VanishAPI==null){
                    VanishAPI = (VanishAPI) createVanishAPI(serviceClass);
                }
                mAPI = (S) VanishAPI;
            }else if(serviceClass.getSimpleName().equals("AmazonAPI")){
                if(amazonAPI==null){
                    amazonAPI = (AmazonAPI) createAmazonAPI(serviceClass);
                }
                mAPI = (S) amazonAPI;
            }
        return mAPI;
    }


    public static void setWSSE(String WSSE) {
        RetrofitCreator.WSSE = WSSE;
        vanishAPI = createVanishAPI(VanishAPI.class);
    }

    public static void setAmzToken(String token) {
        RetrofitCreator.AmzToken = token;
        amazonAPI = createAmazonAPI(AmazonAPI.class);
    }

private static <S> S createAmazonAPI(Class<S> serviceClass){
    httpClient = getUnsafeOkHttpClient();
    builder = new Retrofit.Builder()
            .baseUrl(Constants.URL_AMAZON)
            .addConverterFactory(JacksonConverterFactory.create());

    if (AmzToken != null) {
        Log.w(TAG, "WSSE not null!");
        Interceptor interceptorSecure = new Interceptor() {
            @Override
            public Response intercept(Interceptor.Chain chain) throws IOException {
                Request original = chain.request();

                // Request customization: add request headers
                Request.Builder requestBuilder = original.newBuilder()
                        .header("Cache-Control", "no-cache")
                        .header("Accept", "application/json")
                        .header("Authorization", "Bearer " + AmzToken)
                        .method(original.method(), original.body());

                Request request = requestBuilder.build();
                return chain.proceed(request);
            }
        };
        httpClient.addInterceptor(interceptorSecure);
    }

    OkHttpClient client = httpClient.build();
    Retrofit retrofit = builder.client(client).build();
    return retrofit.create(serviceClass);
}

(...)
}

To get it in each Activity I use :

amazonApi = RetrofitCreator.createService(AmazonAPI.class);