If you goto the Beam ‘Room’ Settings in ‘Settings/System’ in the Sonos App, there are two useful adjustable (buffering) options there called “Group Audio Delay" and “TV Dialog Sync” (slider-bar) - try adjusting the values available there, until you get a happy balance of uninterrupted, but (hopefully) timely audio. 

This makes it a bit better, still it is not as it should be. It is not as a sonos should work/sound. 
what is the reason that my roam has this lagging sound while my other speakers don’t? 

TV audio has an audio lag on all types of ‘grouped’ Sonos devices, not just the ‘Roam’. It’s because the wired HT player and it’s own ‘bonded’ surrounds mainly use a 5Ghz fast Ad-hoc wireless connection (linked directly back to the main player), so that all play in sync with the video on the TV screen, the ‘other’ grouped (not bonded) players use 2.4Ghz buffered audio with a 75ms delay (that keeps the players in sync over WiFi mostly for music audio) but they are then slightly out of step with the TV audio… it’s fine if the speakers are in a different room and/or a fair distance away from the listener, but not always so good in the same room or when close by.

You may only see this issue with your TV audio - music audio is fine as that audio is buffered on all players. However the tools I mentioned earlier, particularly "TV dialog sync” can assist with bringing some TV audio formats (like PCM stereo) in sync across all ‘grouped’ players and the "Group Audio Delay” feature may assist where some wireless networks are unable to cope well with TV audio bandwidth and help to prevent ‘grouped’ audio dropouts.