First, read the English article below.

If you aren't seeing a new version but you know that there is one available, you may need to adjust your Software Updater settings.   Open the Ubuntu Software Center. Click "Edit" → "Software Sources". Click the "Updates" tab. Find the "Release upgrade" section or "Notify me of a new Ubuntu version". Select "Long term support releases only" or "For long-term support versions". Problems with the upgrade process typically stem from running an outdated and unsupported version of Ubuntu. You'll need to either upgrade to each subsequent version until you reach the one you want, or you'll need to perform a fresh install of Ubuntu. 

Now, please write a short abstract for it in Indonesian. Abstract:
Lakukan beberapa langkah berikut jika Software Updater tidak menampilkan Ubuntu versi baru. Lakukan langkah ini jika proses pembaruan gagal, atau Software Updater tidak memperbolehkan Anda untuk menerapkan pembaruan versi terakhir.