Hi @Feride Kr Can you give the full model number, some series 5 Tv's are older than others,need to give some Troubleshooting. Anyway it is advisable to check if your model has the latest firmware on the Samsung site . if do not have it can be updated via USB if not available OTA. If not the issue can you reinstall the app if you can not update it, is the problem only with Youtube and not only and other apps?
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
