These companions just want to make things difficult!
Every time I try to equip my companions with better weapons or armor from what their default is the companions switch back as soon as combat starts.
I understand that one has to force equip (Triangle for PS4), but why won't my companions stay equipped?
UPDATE: It seems that only Preston has the issue of keeping equipped armor on if you leave his armor in his inventory. All other companions appreciate their new getup.
Best Answer
You put some of this in an update to your question, but it should really be in an answer:
I've only had issues with Preston switching back to his original armor, which is a colonial duster. Everyone else sticks with what I tell them. This can be fixed by removing the armor from his inventory. If the armor is not visible when you attempt to trade with him, it should show up once you tell him to wear something else. After that, he mostly cooperates. I have occasionally had him magically generate a new duster and don it after a main Minutemen quest.
Any companion will switch back to their original weapon when they run out of ammo for all the weapons you've given them. Their original weapon uses magic companion ammunition and never runs out. You don't appear to be able to remove the default weapon from their inventory.