If you don't see any options featured below on your database sheets, it may be related to the access rights you are granted. If you have any questions about your access rights or not being able to modify entries on a sheet, please contact your SYSAdmin of the database to check for the proper access rights configurations.
When you are on the form page of an entry, and you would like to edit this entry, either double clicking on the field value, or pressing F2 will take you to the editing mode. You can also navigate from Tools > Edit Entry.
You may update the field values just like the way you would with other forms. If you would like to clear a field value while editing, including text or uploaded files, you can click on that field and press delete or backspace. In addition, Autocomplete (popping-up related selections in the drop down menu when typing characters in the field) is supported in Selection, Multiple Select or Select from other sheet field types.
Remember to save all changes before you leave the editing mode via the Save button at the upper-left corner.
To upload a file, you can find and select it from your computer or drag and drop it into the field.