To clear excess cache entries click OPTIONS | Clear Unused Cache Files. It's wise to do this before beginning a new project.
There are a number of ways to make individual cuts from a single imported file...
Select the master file in the bin and press <ctrl-C>. For as many cuts as you want, press <ctrl-V>. This will duplicate the thumbnail without the need to reload the file. Go back to the master thumb and repeat the process if more copies are needed.
Click on one of the dupes (not the master), position the scrubber (red line) under the preview window where you want the cut to start. Click SET START. Reposition for where you want it to end, click SET END. Go to another dupe and make new selections, etc. Lastly, drag the thumbs to the timeline in the desired order, where they can be rearranged if necessary. Or right-click on a bin thumb and click the desired placement from the drop-down menu. Or, with a Bin clip selected, click the chevron at the right of the ADD button to see placement choices.
Another method...
Place the full master video on the timeline. Create and IN/OUT split pair to isolate desired content. Drag that content (between the splits) to the bin. It is removed from the timeline and becomes a numbered clip, similar to the above. You can create all clips in the bin, then drag them back to the timeline.
In any case, Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar.