Originally posted by kjphilippona I am thinking of selling everything and trying another brand that is capable of taking indoor pictures without all the ISO noise loosing the sharp detail.
To be blunt it is the photographer not the gear. Changing to another brand at any reasonable price is not going to change anything. You could move to Nikon similar models but wait they use the same sensor as Pentax. You could move to Canon, but wait their sensors are not as good as Pentax/Nikon. Sony? Panasonic? Fuji? You might find a model or brand that is somewhat better at what you want to do, but you will still need to learn to how to use it and use flash. No appreciable gain IMHO.
You could move up to a newer model, like the k-3 or D7200 and you would see a marginal difference. You could move up to something like the D810 and see some difference, but at what cost? And you will still need flash in many cases.
No, the answer is to learn to use the gear you have. Using flash properly is not easy, but it is not impossible either. It takes study, and practice but really it is the only way to do what you want.
Try reading these:
On-Camera Flash by Neil van Niekerk
Off-Camera FLash by Neil van Niekerk
Understanding Flash Photography by Bryan Peterson
Originally posted by kjphilippona Lightroom 5, but do not use it much, I don't have the eye to get my pictures looking good
And you need to learn Lightroom. Shoot in RAW and develop in Lightroom. Easy? No. Very much no. But part of being a photographer.
If you want to change brands that is up to you but honestly there is not any significant difference between the brands at this point. Some better, some worse, but nothing better enough that it is "capable of taking indoor pictures without all the ISO noise loosing the sharp detail". That is physics, not camera brand.