How do you repair scratches on a decking?

Both timber and composite can scratch, though the tendency is higher in timber than in composite. Moving heavy objects or furniture is the primary cause of scratches on boards.
While scratches might make your deck less pleasing, it is advisable not to repair them because, over time, they blend in with the rest of the deck. However, your composite deck has a noticeable scratch use a soldering iron to level the scratch as well as blend it with other areas of the deck.
Alternatively, you can touch up small scratches, and scuffs use a tough-up concealer.

For wooden decking , you can paint or stain the deck.
For deeper scratches or substantial damage on the deck, a replacement me be required.