Once you set up 2 strategies to pull down at the top of the amr page Krosus and Spellblade it will work like this
If you have 2 different specs for Single target vs AoE its REALLY easy
AMR for Single target vs AoE with 2 different specs
1. Select Spellblade strategy for AoE gear
2. Clear any single target specific forced gear choices you might have
3. Run Best in Bags
4. Export your setup
5. Do same for Krosus as above.
6. Now as you switch between your two specs your gear goes with you painlessly.
There is an added step using Outfitter or similar gear saving if you use the same spec for 2 different gear sets (currently until AMR updates this).
So for my example I go Druid, Balance, and for aoe I have one set that AMR suggests for Spellblade. But for Single Target I have a set I like for Krosus with a specific legendary and other gear choices. Occasionally I have to lock in AMR gear to get exactly what I want.
AMR with Single vs Aoe Strategy for One Spec
1. You want to export or update your AoE strategy. Switch strategy to Spellblade
2. Do any importing from addon you need to
3. Make sure you don't have any items that you've locked in from single player since switching strategy doesn't know about gear for different specs you might have preferred yet
4. If any changes were made, save and update your gear
5. Finally click Best in bags (make sure you have the order of specs there that you use most)
6. Now you'll have your AoE gear choices
7. Export to addon
8. If you want you can clone this setup in outfitter to a new gear set in game like for me I might make "Druid Balance AoE" gear set and update that
9. Go back to begiinning for Krosus and do it for your Krosus (single target) gear.
Now you can hold off using the addon for a few days/weeks until you get some strong new gear. Check your gear sets and make sure you like the options since some gear addons may switch sets automatically when you change talents and this can get confusing fast.
PS - After writing this up I just realized I did it in reverse order of "Krosus then Spellblade" but it amounts to same thing. Point being 2 make 2 separate strategies. The order should not be important.