Yellow marks on white clothes

[Gobolino80]

I’d be really grateful for tried and tested methods to remove yellow sweat marks from white clothes. I’ve so far tried the spray Oxi Action and plenty of time on the line in direct sunlight but it’s not shifting.

I saw something online the other day suggesting a paste of bicarb and white vinegar but I haven’t tested it yet!

Marseille soap is my go to. I've heard washing up liquid talked about recently but not tried it.

Rub in regular washing up liquid with a toothbrush, leave for an hour. Then soak in oxi action whites for as long as instructions say you can, then wash in machine with bio laundry liquid. Then line dry in sun. Worked pretty decently on suncream stains which had turned yellow on whites- the same issue as deodorant which is that it has body oils in it.