it's also right ! I think this depends on the context http://deutschinallerwelt2.blogspot.com.au/2014/02/136-word-order-in-main-clause-ii.html
With capital S, Sie only means (formal) you (Can't tell, though, if it happens to be the start of a sentence. Then you have to rely on context)
With lowercase s, sie means either she or they - you can tell them apart because the verb form will be different, e.g., "sie mag/sie mögen"
Later edit The second paragraph above only applies when "sie" is the subject. If "sie" is the object of a sentence - as it is here - the verb form tells you nothing. It means either "her" or "them". Both "Everyone likes her" and "Everyone likes them" are accepted answers.
If there is any confusion as to which noun/pronoun is nominative and which is accusative then the nominative should come first. Here Alle and sie can both be plural and are the same in nominative as accusative, so the grammar endings provide no clue. There is no other context to suggest that sie is the nominative so we must go with the word order: Alle as nominative and sie as accusative.
At this language level I think this should always be the case, it gets too confusing otherwise. It's true that DL has a couple of examples with the plural accusative before the plural nominative ("Hausgeräte haben meine Eltern" of similar) but I think that is a poor sentence at this level because although meine Eltern would be much more common as the nominative, without clarifying sentences either side of it you can come up with examples where the appliances "have" the parents.
1- everyone love her 2- everyone love them
Those two are not correct English -- "everyone" takes a singular verb (with -s). And mögen is "like", not "love".
Besides that, though, alle mögen sie can indeed theoretically mean any of "everyone likes her, everyone likes them, they like everyone".
But it would be unlikely to be "they like everyone". I can't explain why, but it would sound odd to me to put it in that word order.
So the accusative form of "sie" is "sie"?
(And this causes Germans learning English similar problems to English speakers - for whom the objective form of "you" is "you" - learning German. They will say things such as "I like she" or "Do you know they?".)
Why ist it alle and not jeder?
Both alle mögen sie and jeder mag sie are possible.
Literally, they are "all (people) like her" and "every (person) likes her", respectively, so the first one focusses more on the entire group as one, while the second more on every individual person individually.
Both would best be translated as "Everyone likes her".
What is the difference between "alle" and "alles"?
Still the same as when -Goca- explained the difference 6 years ago.
Still the same as when Dung.13.1 explained the difference to 2it 6 years ago.
The language hasn't changed in those six years.
Was there anything about those explanations that you felt was lacking? How could they have explained it better?
What about their explanations made you want to re-ask the question?