I am using Two different flows and executing through checkBox selection. And also using Drop down tool. Drop Down values differ for each check box flow. How can we update DropDown tool values based on CheckBox selection?
I think what you're asking (although I'm not sure) is how to have the selections made via checkbox tool by a user in App#1, populate a drop down tool in App#2. If that's correct, you'll have to make use of chained app functionality. App#1 will need to end up in an output that will be the values for the drop town in App#2. You chain the apps together, but publish App#1 making sure you don't mark the output to be used in the dropdown as an asset.
Here's another Community posts where I explain it with an example in the comments:
https://community.alteryx.com/t5/Alteryx-Server-Discussions/Chained-apps-Use-an-output-xydb-of-one-a...
If I'm not understanding your question and this is not what you are looking for, then you'll have to provide a lot more detail including screenshots and configurations of exactly what you did, and how you want it to work.