How to add variation to a game on Arena Chess? Suppose I load a game from PGN on arena. Check screenshot.

If I want to add a variation to a main move, how can I do it? Is there any option to add a variation?
Go to the move where you want to insert a variation and make an alternative. Then, a popup will open:


New variation will create a new variation (what you actually want).
Overwrite will overwrite the main move and all the next moves.

If you want to make a variation mainline, then right-click one of its moves → Upgrade variation.