DIAGNOSIS You're running into a common audio sync issue called a 'center channel' or 'dialogue' problem. It often happens when the soundbar isn't properly decoding a surround sound signal, leaving dialogue faint.
FIX The first thing to try is changing the audio output setting on your source device (streaming box, game console, or TV app). Look for an option like 'Audio Format' or 'Digital Audio Out' and change it from 'Auto' or 'Bitstream' to 'PCM' or 'Dolby Digital'. This sends a simpler, more compatible signal the soundbar can handle consistently. Next, use your Bose remote. Press the 'Voice' button. Each press cycles through increasing levels of dialogue enhancement. You'll hear a tone. Give it a few presses and test with a show.
IF THAT DIDN'T WORK It could be a specific mode causing it. Press the 'Soundbar' button on the remote until the light is solid white for 'Standard' mode. Avoid 'Adaptive' or 'Dialogue' modes for a moment as a test, as they can sometimes behave oddly with certain content.
HEADS UP Some streaming services and Blu-rays have very dynamic audio mixes by design. The 'Voice' button adjustment is your best friend here—don't be afraid to crank it up just for dialogue-heavy shows and then turn it back down for music.