For context, I want to make clock arms rotating around a clock, but they won't stop rotating around their centers. The center is NOT the origin.
You use circle geometry to set the position of the hands images, setting a bearing for the sprite.
It is actually easier to do this by using canvas elements, e.g. drawline
See the cue stick manipulation code in
The cue stick is allowed to rotate around the cue ball, but always points to it.
The arms should be sprites, because the arms are supposed to interact with another sprite
What other sprite will the clock hands interact with ?
If you look at the blocks HERE, you will see how to set up your clock "hand" sprites (credits @SteveJG )
The trick is to make the sprite images "long/wide enough" so that they can rotate around the centre (origin)
Nowadays, once you set the image to a sprite, you can set the origin to be 0.5/0.5 so that it is in the centre
How do I make the arms continuously rotate around the clock face?
They will interact with the player. Btw, they don't need to spin like actual clock hands, they should just spin normally
Once upon a time by default ALL sprites rotated about a sprite's upper left hand corner. App Inventor in the past year changed the rotation behavior to rotate about the sprites center as the default.
The developer can change where the sprite rotates as described in Drawing and Animation
Initially you said ". I want to make clock arms rotating around a clock,"; now you are indicating that isn't at all what you want to do.
The the rotation axis is the center of the sprite by default.. What do you mean by spin normally?
The thread has several examples shown in this thread that provide the blocks for the old and present ways of spinning a sprite and example aia files. Perhaps you will share with us which example you have tried? 
(This was solved)
"normally" means to rotate continuously (as in every <1 s) instead of every (s)/min/h like actual clocks.
I DO want to make clock arms, but i DON'T want them to spin like actual ones; I want them to spin continuously. (the term "continuously"/"normally" explained below the first quote)