These options affect all users.
Tick "Required Work Description" to force users to enter work description when logging time. Please note that "Required Work Description" enforcement works on Work Time Calendar level. The work log records still can be placed through Log work menu on Issue details screen and through direct calls to JIRA REST API.
"Clear cache interval" is used for configuring automatic purging of the worklogs cache. Work records are cached in your browser after retrieval from the server. Please be aware that worklogs are reloaded whenever users click My Work menu or refresh the page.
"Managers Group" can be used to configure who can see reporting of other users' on the Calendar and Timesheets tabs. If the Anyone option is set, then all users can view others' work logs. When some group is selected, then ability to see others' reporting will be limited to members of this group.
Please note that "Managers Group" option only hides appropriate UI elements and limits functionality of the Work Time Calendar. The work log records of other users still can be retrieved through direct calls to JIRA REST API.
Enable "Reported Colors" and/or "Planned Coors" to visually indicate if there is not enough or too much planned or reported hours. Here you need to set minimum and maximum daily hours. Daily totals that are below the configured interval are displayed in orange while exceeding totals - in red color. So every user sees if they have planned and reported the expected number of hours.