Assignment rules are tools that allow administrators to automatically route records to users or queues based on certain criteria. For example, an assignment rule can assign cases to different queues based on case priority, origin, type, or other fields. Assignment rules can be triggered when records are created manually, via email, web, or API. Assignment rules consist of multiple rule entries that define the criteria and actions for each assignment scenario. References: https://help.salesforce.com/s/articleView?id=sf.customize_leadrules.
htm&type=5 https://help.salesforce.com/s/articleView?id=sf.customize_casesupport_assign.htm&type=5

To make a quick action available on the Salesforce mobile app, you need to add it to the Salesforce Mobile and Lightning Experience Actions section of the page layout. You can use the Page Layout Editor to drag and drop the quick action onto the section.
References: https://help.salesforce.com/s/articleView?id=sf.actions_in_lex.htm&type=5 https://help.
salesforce.com/s/articleView?id=sf.customize_page_layouts.htm&type=5

To automate applying discounts on opportunity products when an opportunity is won, the administrator should use Flow Builder, which is a tool that allows creating complex business processes with clicks. The administrator can create an autolaunched flow that runs when an opportunity is updated, checks if its stage is
"Closed Won", and updates its related opportunity products with discounts from a formula or variable.
Approval Process, Prebuilt Macro, and Formula Field are not able to update related records based on criteria.
References: https://help.salesforce.com/s/articleView?id=sf.flow_build_overview.htm&type=5

Permission sets are used to grant additional permissions and access settings to individual users without changing their profiles or requiring a new profile to be created. You can use permission sets to extend users' functional access without changing their existing profiles. To meet the request of giving comprehensive edit access on Campaigns to a few marketing users who have read-only access by default, you need to create a permission set with edit access on Campaigns and assign it to those users. References: https://help.salesforce.
com/s/articleView?id=sf.perm_sets_overview.htm&type=5

Setup audit trail is a tool that allows administrators to review recent configuration changes made in their org.
It shows a list of up to 180 days of setup changes made by anyone in the org, including the date, time, user, and type of change. It can help administrators track who made what changes and when, and troubleshoot any issues caused by configuration changes. Critical updates are notifications that inform administrators of new features or enhancements that may impact their org; they do not show configuration changes made by users.
Debug logs are records of database operations, system processes, and errors that occur when executing a transaction or running unit tests; they do not show configuration changes made by users either. Field history tracking is a feature that allows administrators to track changes to the values of certain fields on records; it does not show configuration changes made in setup. References: https://help.salesforce.com/s/articleView?
id=sf.monitorsetup.htm&type=5