Minecraft – When I shift double click to move all of one item in Minecraft it doesn’t work

/execute @a[score_att_min=1] ~ ~ ~ scoreboard players set @e[r=10,score_att= = 0] targ 1

You have a second equals sign, breaking syntax. The parameter is ignored for being invalid, thus the parameter set only contains r=10.

/execute @a[score_att_min=1] ~ ~ ~ scoreboard players set @e[r=10,score_att=0] targ 1

However, keep in mind that players & non-player entities will not have a score of 0 to detect if they are not instantiated into the scoreboard. That is, if the targets have not had a score set yet, you won't be able to target them with score_att=0 because they have no score whatsoever.

A quick fix is to add 0 when necessary, which preserves the scores of those that are already tracked but forces other targets that aren't tracked to have a default score of 0.

/scoreboard players add @a att 0

To get the item from a "/give" style NBT format to a "/replaceitem" style JSON format, you have to actually change quite a bit:

• You have to escape the quotation marks (but I think you know that already)
• You have to escape the backslashes: \\\"
• You have to add the "id" tag to indicate that it should be a bow: "id":"bow"
• You have to add the "Count" tag so that it isn't a 0-stack: "Count":1
• You have to put the item NBT into the "tag" tag: "tag":{"display":...}
• In 1.14 Name and Lore are JSON as well, so now you have quotes in JSON in JSON and the amount of backslashes grows to seven in a row.

/tellraw @p {"text":"Test","hoverEvent":{"action":"show_item","value":"{\"id\":\"bow\",\"Count\":1,\"tag\":{\"display\":{\"Name\":\"{\\\"text\\\":\\\"\\\\\\\"Send Zombies To Mars\\\\\\\" Bow\\\"}\",\"Lore\":[\"{\\\"text\\\":\\\"Knockback MMMM\\\"}\",\"{\\\"text\\\":\\\"Costs 40 Points\\\"}\"]},\"ench\":[{\"id\":49,\"lvl\":5}],\"Unbreakable\":\"1\"}}"}}