Skyrim autosaves

It is worth noting that when you get the 'Bounty Removed' message, it is accompanied with a value of how much bounty was removed. If the bounty removed is lower than the bounty you gained from killing everybody then you will still have a bounty with that hold - which would explain why the guards still come after you.

Also keep in mind there are some known 'issues' with the way Bounties work;

• Friendly fire on an ally such as Imperial Soldier or Guard raises bounty.

• Bounties can be accrued even if witnesses are not present. Sometimes chickens, dogs, and other wild animals can be witnesses to a crime as they are considered entities.

• Guards will sometimes attack criminals even if the crime was unseen and no bounty was placed. They will not give the option of yielding. Sometimes only a few guards will attack, while the rest go about their normal business.

Armor items have a base armor rating (based on the type of armor, eg Steel) that cannot be changed - but you can improve the effective armor rating (i.e. the number that appears on the item when you have it equipped) in a few ways:

1. Increasing the level of the armor skill relating to that type of armor (eg increased Heavy Armor skill will improve the rating you receive from heavy armor)

2. Unlocking armor perks in the respective skill tree (the first perk in the tree, i.e. Juggernaut for Heavy Armor or Agile Defender for Light Armor)

3. Unlocking the unison perk in the respective skill tree (Well Fitted for heavy armor, Custom Fit for light armor) and wearing four pieces of the same armor type to make it work

4. Improving the item via Smithing - the higher your Smithing skill, the better improved your armor will be, and having a Smithing perk associated to that armor type will also help

5. There's also a perk you can unlock through a quest which will give you a permanent +25% bonus if wearing Dwarven Armor.

Any of these methods will take effect immediately for armor you're already wearing - you won't need to create a new set to see the benefits, although you may need to unequip and re-equip your armor items before the benefits will be visible.

Bearing all of the above in mind, there is a hard cap of 80% physical damage reduction (567 in full armor without a shield, 542 in full armor with a shield, and 667 if unarmored), beyond which you'll see no additional benefits. The cap is easily reached before maxing out all of the above methods - so, for example, it's possible to achieve the armor cap with Steel armor if you've maxed out all other benefits; you don't necessarily need Dragon Armor to do it.

Source (UESP)