Step 3 of the offer editor, Look and texts, also sets the words shoppers read. This video covers two groups there: Option texts and Names. To open them, click Bundles & Discounts in the app, open a volume discount, and click Look and texts in the steps on the left. How the offer looks has its own guide.
What this video covers
When your tiers count items, pick 2 items, 2 pack or Set of 2 in Name options as to title them all at once. With 2 items, Word for one and Word for more than one give titles like 1 bag, 2 bags and 3 bags. Pick Your own titles to write each title yourself; typing over a title switches to it too. If some tiers have titles you wrote, you're asked before they're replaced, and their translations stay as they are.
Each tier's box: Title (the option's name), Subtitle (the line under it), Savings badge (beside the title; leave it empty to hide it), Badge (the label on the option's top edge, like Most popular; leave it empty for none), Badge style (Simple or Most popular) and Text under price (a short line under the price, like a price per bag).
Variables adds a value that changes with each tier, such as Per item price, Saved percentage or New total price; the line under the field says what it shows. Under Calculate, Price per day divides the tier's total by 30, and you can change 30 to any number. Badges show as typed, without variables. Translate adds other languages; leave a language empty to use the default. Text under price has no Translate and shows in your store's main language.
Names: Title shoppers see is the heading above the offer; switch off Show the title on your store to hide it. Name at checkout is optional: shoppers see it next to the discount in the cart and at checkout, and it isn't translated. Leave it empty to use the title; a tier's own Name at checkout, in that tier's settings, wins over it. Name in your admin is only for you and your team; Shopify's Discounts page shows it in brackets after the title.
On the Legacy widget, each tier has only Title and Savings badge, the badge shows even when it's empty, the title always shows, and Description is under More options.
On your store: Bundle & save above the offer, 1 bag, 2 bags and 3 bags, the price per bag under the 2 and 3 bag prices, and Bundle & save under the product in the cart, above the discounted price.
In short
When your tiers count items, Name options as sets every title at once; Your own titles lets you write each one.
Leave Savings badge or Badge empty to hide it. The Legacy widget always shows the savings badge.
The Most popular badge style adds sparkles only when Match my store on Volume discounts is off, in Design, Display settings.
Text under price shows in your store's main language and can't be translated.
Name at checkout is optional; leave it empty to use the title.