vietnamese font error, please help

Dear All Solidres user and support ,
I use Solidres 0.9.4 on my joomla 3.5 site (duo languages English and vienamese) . I meet a trouble when i creat list room types , the font error in vietnamese as the images below . i dont know how to improve , please help me to solve this problem .
sorry , my english is not good .
Thanks a lot .

Dear Mod ,
Thanks for your quikly support ,
First , i install from a quickstart joomla that i buy on themeforest , some tables in database are not utf8_general_ci. Then I changed all table in my database to utf8_general_ci . Now all my database tables are set to utf8_general_ci but the problem could not be improved .
Thansk .

Yes , I tried many times , can not improve .
You can try with user and password as bellow:

Please support me .
Thanks .