when i want to add and remove stuff from barrels and crates it lets me and when i do it and i go in game it doesnt do those changes ive tried reseting the sever and restarting and updating oxide and even the plugin i dont know what to do

Are you editing the oxide\data\BetterLoot\LootTables.json  with the plugin unloaded, then save , then reload plugin ?
If you edit it with the plugin running it wont save anything,  you also have to check file with a json validator because if you have made any syntax errors it will revert to default.