It's a good best practice to save your changes frequently to keep from losing work. In Smartsheet, you save changes by clicking the Save button on the toolbar.
The shortcut key for saving is Ctrl+S (Windows) or Cmd+S (Mac).
To configure auto-save options, click Account > Personal Settings > Settings.
See and Save Unsaved Changes
When there are unsaved changes in the sheet, the Save button will become selectable. When you select the button, the icon will no longer be selectable and you'll know that all the changes you've made to the sheet have been saved.
To save a sheet outside of Smartsheet, export it to a format of your choice.
Refresh a Sheet to See the Most Current Version
If you've shared a sheet with others, those people will see the changes you've saved the next time they open the sheet.
If people are viewing the sheet at the time that you save your changes, Smartsheet will either refresh the sheet automatically or prompt those people to refresh the sheet to see the new information. The prompt appears as a blue refresh symbol next to the sheet name at the top.
To refresh a sheet, click the refresh symbol or click File > Refresh.