I cannot export my file in high-quality format

Hello,I am a Chinese fan of your software,but there is a problem I cannot solve.I have devoted a lot of my energy to composing a piece of music using your software for around a fortnight,hoever,I can only export my works in mp3 format,which reduces the sound quality,making it sound noisy.As a matter of fact,if I choose wav or flac format,the software will popup a window to tell me that''Unable to write'',but if I choose mp3 format,it will operate normally.In this case,I have tried everying I can do,but nothing works.I'll appreciate it if you can give me a hand on time!Really thank you!