So... I open the game and there's only one resolution available which is 1280x768 but I want to play in my computer's resolution but it doesn't let me change. I've seen another post with a similar question but it didn't work.

+1 on this issue, and sent a support ticket on this.

From a search I have done, it appears to be a generic issue with various games under Windows 10.
It might be a Microsoft issue (I doubt it since it works well for most games), or game clients may need a different bit or code for handling screen resolutions under Windows 10 (most likely answer).