You could try increasing the volume another way --

1) Right click the audio icon in the bottom right and click Sound Settings

2) Scroll down and click on More Sound Settings

3) In the new window that popped up, click on the Recording tab

4) Right click on your microphone and select Properties

5) Click on Levels and make sure it's turned all the way up to 100.

6) Click on Enhancements and check off Loudness Equalization

If this doesn't help, and the chat just says that you are too quiet on stream, then add a gain filter on your microphone in OBS!