What should I choose in this sentence, make rather than do?
What should I choose in this sentence, make or rather do?
Neither expression is the right choice in this situation.
If you have not decided yet, and are contemplating the decision, then simple 'or' should suffice:
What should I choose in this sentence, make or do?
Additional words you can use are "perhaps", "maybe" and similar.
What should I choose in this sentence, make or perhaps do?
If you lean towards one choice already, then your "rather... than" could work, and then it's not a question anymore, it's a statement:
What should I choose in this sentence? Rather make than do.
The second sentence here is incomplete, the predicate is missing, but colloquially, and in ruminations (talking to yourself), they are fine.
Only can be an adverb or an adjective. Furthermore, as an adverb it can modify a verb or an adjective.
I only went there to see Becky.
I took the only piece of candy left.
There was only candy left.
Because of this, the position where only appears is crucial - the speaker/listener will associate it with the closest word.
So all of your sentences mean different things:
I only sell apps to the young person.
You don't do any other action besides selling apps to the young person.
I sell only apps to the young person.
You don't sell anything else but apps to the young person.
I sell apps only to the young person.
You don't sell apps to anyone except the young person.
I sell apps to the young person only.
You only sell apps to one person, and that person is the young person. This isn't too far off from the previous meaning.
Furthermore:
Only I sell apps to the young person
No one else but you sells apps to the young person
I sell apps to the only young person
There is only one young person and you sell apps to him.
Best Answer
In OP's examples, then means next, [immediately] after [whatever time/event was previously mentioned].
The concept of transitional tags seems useful here. Depending on your point of view, you could say then conveys either addition or time sequence - but I'll go for the latter, since that's obviously the category for related alternatives such as first, next, finally.
My initial inclination was to say then can happily go before or after the subject (I in OP's example), and leave it at that. But it's worth pointing out that although this is true, and applies equally to first and next, it doesn't apply to finally in quite the same way...
There are some contexts where (2c) above is acceptable, but it doesn't really work in contexts where the only sense of finally is "next and last". If finally comes after the subject, there's invariably a strong implication of "next, and at long last".
I think what this suggests is that all these "transitional tags" should normally come first in the statement, but by custom and practice native speakers don't mind moving small short words to between the subject and verb. But because that's slightly "unusual" positioning, we tend to look for a possible semantic difference.
In practice there doesn't seem to be any credible semantic difference depending on whether we place then before or between subject/verb, so it's just a stylistic choice. But there certainly can be a subtle difference according to the position of then...
In (3), then has the normal sense (chronologically after), but in (4) it has the more "extended" sense of as a result [of what came before], in that case, therefore.
To summarise: there's no grammatic or semantic difference in OP's specific examples, but if you're looking for general principles, you'll be safer if you put any transitional tag first in a statement.
Finally, here's an NGram showing how usage has shifted over the past couple of centuries.