I am not a native speaker, I do not know how to say this properly: "It should be always on", or "It should always be on"? Is there any difference?
There is a slight difference. Most often one would say, "It should always be on."
In "It should be always on," always is modifying the word on, and on is an adjective describing it. Therefore, using this phrase gives the sense that you are describing "it" as "always on." This makes "always on" seem to be a momentary property of "it", and not a continuous state as you would probably like to convey. This would be like going to the settings of a program on your computer and selecting an option titled "Always on". Additionally, in the everyday sense this gives the impression that you are simply telling the audience a property of "it", and not giving an instruction to keep "it" on. The audience will still likely understand what you mean, however.
In "It should always be on," however, always is modifying the verb be. You are saying that the state of being of "it" should be "on" continuously (always). This is like going into the program again, finding an option titled "On", and making sure that the option is always selected. Again, in the everyday sense, this might be more interpreted as more of an instruction to always keep "it" on, if used in that context.
First choice-"It should always be on".
Always is an adverb of frequency.
- When you're tempted to write "always," "usually" can be a safer choice.
Usually, always is placed after the verb " be": He is always late.
between the aux.verb and the main vb.: She will always be my mentor.
Always can position itself at the beginning or end of a sentence, though its not necessarily true of all adv. of frequency.
To emphasize, we can say-
Always it should be on. It should be on always.
At the end is unusual - we usually only put it there when we have forgotten to put it in earlier.
Those mean the same thing: whichever one you say, I'll know what you mean. However, the first one sounds awkward.
The second, "It should always be on" sounds more natural, because the thing that is always happening is that 'it' is 'being on'. 'Being on' is a state that could occur for a short time, or for a long time, or always.
Saying that something should be 'always on' is a bit awkward, because 'being' is something that happens in the present, but something can't happen 'always' in the present, just over time.