In this regard and in this respect refer back to an idea expressed in the previous statement.
Consider your example:
There is a shortage of skilled labor in this city. Decision makers
should do something in this regard.
The second sentence can be paraphrased:
Decision makers should do something about that.
where "that" refers to the shortage of skilled labor in that city.
Or this example:
The internet speed is low in this country; in this respect, it is one
of the worst countries to use internet.
The second sentence could be paraphrased:
... in terms of speed, it is one of the worst places to use the internet.
or
when the criterion is speed, it is one of the worst places to use the internet.
"in this respect" refers to the slowness that is mentioned in the preceding clause.
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
You're exactly right, and I don't think this is a silly question at all! Parse the sentences like this:
This is a denial of the statement "I always get up early". It's saying that is not true. So as you said, this means that getting up early doesn't happen all the time, but it can happen some of the time.
This is an affirmation of the statement "I don't (ever) get up early", which would probably be more likely to be said like this:
Both sentence 2 and 3 mean that the speaker does not ever get up early.