Hi @SercanErdemYilmaz, sorry to hear you're experiencing issues when updating your course description. Some instructors have found that refreshing the page and cleaning cookies in the browser can solve the issue, but If you are still having this problem after trying that, please reach out to our team at firstname.lastname@example.org, they will be happy to help you with this.
About enabling the 1080p video quality (Adaptive Streaming), this is also something you can request from our support team writing to the email above.
For reference: Here's How to Reach Udemy's Support Teams
Udemy Community Team