使用illustrator修改字体时，将鼠标放置在某一adobe fonts的字体上预览时能看到所选文本更改为指定字体，但是点击后字体并不更改，还是原本的字体样式，现在能使用的还是自带的几个原始字体，

@xu_4500 that's weird, the video shows you did everything correctly with the text tool. It typically is a syncing issue between the Creative Cloud desktop application and Illustrator itself. Sometimes that happens to me, and what I have done, is make sure I am in the correct account. I have two differe nt Adobe ID's, so sometimes I am usin the wrong ones. Make sure you are log in. Now, speaking for myself here, I just turn it back on and off. I turn it off. Count 5 Mississippis and turn it back on. I can't remember I restart Illustrator after doing so. Knock on wood, it hasn't happened for me awhile. I might have restarted it! 

If by chance it's still glitchy, I will go into Font Manager and validate the font. On a MAC, open Font Book from your Applications > Utilities folder, select all your fonts, and go to File > Validate Selection to check for corrupted or duplicate fonts. 

On a PC, open the Control Panel and go to the Fonts folder to validate them. That normally does the trick!

And worse case scenario, you can always clear the font cache! Good luck!