Before changing a Stand, check which slot is active and whether you want to keep what is in it. The community slot guide reports that an empty slot lets you try another Stand while retaining the existing one, whereas Rokakaka removes the Stand in an occupied slot. These slot and item interactions still need confirmation in the current release.
Choose from the options you receive
BloxInformer describes Stand Arrows as offering three random choices. Compare the options actually shown to you rather than planning around selecting any Stand from the full roster.
For a rough comparison, PGG's guide describes Sandman as a movement option, Tusk Act 1 as a ranged option and Star Platinum as an aggressive combat option. Those are qualitative descriptions, not measured rankings or a guarantee that these choices appear together.
Choose for the problem you want to solve in your next run. Read the offered abilities and consider whether you can use them while navigating the race or dealing with another player. A familiar option is worth learning before spending more resources on a replacement.
Keep or replace your current Stand
The following branches follow the community account linked above. Check the active slot and current item description before any use that could remove a Stand.
Check the active slot
The community guide reports using an empty slot to retain the existing Stand.
Pause before clearing
Do not use a removal item on a Stand you want to keep.
Confirm what you remove
Reported sequence: Rokakaka to clear, then a Stand Arrow for another draw.
Decision aid based on the linked community guide. Current slot and item behavior needs confirmation.
If an arrow does not replace an equipped Stand, check the slot before trying more items. The community account reports clearing the occupied slot first or selecting an empty one.
Slot capacity and unlock conditions should be read from your own menu. Do not assume that a paid slot is necessary to make your next choice.
Crafting another arrow
The same community guide reports Stands → Craft as the route for combining Stand Arrow Fragments. Read the recipe and required quantity shown in your game before confirming. This does not establish a fixed fragment cost, drop rate or guaranteed source of fragments.
After choosing, return to the beginner controls to find your Stand input, or review the Stage 1 and Stage 2 objectives for your next run.