browser's chess to old chess version

Can i use browser's chess and switch the old chess.com in that browser…

Not exactly sure what you are asking. 

Until v2 goes away you should be able to switch between versions.

There is a link in the menu in v3.

There is also a link at the bottom of most pages on v2, saying Try the new Chess.com.

Both ultimately use www.chess.com/switch

I don't understand the first Two options butwhen i try chess.com/switch it says,'Did you mean switch to old chess.com? Then click to switch' but there is no option to click…

If you are on the new version and want to switch back to the old version of chess.com , simply click where I have marked with the 3 red arrows. 

Just click in the red banner. I think you have to click the words click here but I am on mobile right now so can't verify. But it always works when I jump to v2 to look up how to do something.

You can also clear the chess.com cookies.