I've had this problem forever, and in my seventies it's a bit worse.
Of course a tri pod and remote shutter release works well but. . . I'd like another option.
Probably should put I this way. Using faster SS as priority, how should I compensate to balance this? ISO or?
Also; if I'm on S (SS) the manual say's that the camera will set the Aperture. OK. If the (A) is blinking does mean I'm out of exposure range?
Thanks in advance.
Another choice is that Indoors (in indoor lighting levels), using a speedlight flash offers extreme motion stopping capabilities, much faster than the shutter speed.
The A blinking in S mode means the lens maximum aperture is not wide enough for the ISO and shutter speed you are setting. Lens hit the wide open limit, and could not open more. I assume indoor lighting, which is not nearly as bright as sunshine. You need wider aperture, or slower shutter speed, or higher ISO. Specifically, you could increase ISO to give it more range in dim scenes.
But... The big problem in general with S mode indoors (dimmer light) is that then the lens is always wide open at maximum aperture. Every shot in more dim light is wide open (and your HI error is asking for wider). S mode is really better like say for sports in bright sun.
I am not a big fan of Auto ISO, but it could be ideal for your goal.
Set camera A mode, and set the aperture you want to use... say f/5.6 in dim light, your choice, but stopping down at least one stop is a good thing for quality when possible.
You can set Auto ISO On, with a Maximum ISO of say 2500 (chose your own maximum ISO).
In the Auto ISO menu, set Minimum Shutter speed there to the value you want to shoot at, say 1/100 or 1/160 second, whatever you think you need.
The meaning is, as dim light drops the shutter speed lower, it will stop dropping at this Minimum, and ISO will start increasing then. It is the Auto ISO threshold. So you will be using that specific shutter speed anytime Auto ISO is actually active, every shot between Minimum and Maximum ISO. It is somewhat like S mode in that way.
Not all things are ever possible, but you do have this choice.
If the Maximum ISO limit is reached and still not enough for the dim light, then shutter speed will continue dropping slower, but you can see this, and perhaps take other steps. Like fully opening the lens aperture, or setting higher Maximum ISO. Or like say flash (you may NOT want Auto ISO with flash).
Watch your results, about ISO and shutter speed and aperture. Be aware of what is happening.