For most people, leave "Keep old versions" on "1 year", which is the default in BackupOnShutdown. It keeps recent backups and a thinner set of older ones, without storing every run forever. You still start each backup yourself, and this setting only decides which older versions remain after a backup finishes.
Where do you change it?
Open "Settings", choose "Backup", and find "Keep old versions". Pick a preset and choose "Save". "Cancel" drops a change you have not saved yet. The same choice applies to every backup, so there is no separate retention for each one.
For any preset other than "Forever", the app explains "Older versions are removed after a backup to save space. Your newest backup is always kept." Saving a different preset doesn't remove anything by itself. The rules are applied after a later complete backup; a run that skipped files doesn't remove old versions. Restore anything you still need before you change the preset.
The setting changes backup history, not your working files. You still start backups with "Back up" or "Back up & shut down", as described in Back up, then shut down.
What do the presets mean?
The six presets keep a mix of daily, weekly, monthly, and yearly versions:
| Preset | Daily versions | Weekly versions | Monthly versions | Yearly versions |
|---|---|---|---|---|
| "1 month" | 30 | 4 | 1 | 0 |
| "3 months" | 30 | 12 | 3 | 0 |
| "6 months" | 7 | 8 | 6 | 0 |
| "1 year" | 7 | 4 | 12 | 1 |
| "2 years" | 7 | 4 | 12 | 2 |
| "Forever" | All saved versions | — | — | — |
Daily means keeping the last version from each of that many days with a backup; weekly, monthly, and yearly work the same way. The rules overlap, so adding the columns won't give you the total number of versions. "Forever" keeps every saved version.
Choose based on the history you need: "1 month" and "3 months" keep more daily detail, while "1 year" and "2 years" keep fewer daily copies and a wider spread of older ones. A shorter preset doesn't necessarily use less space; that also depends on how your files change.
The names aren't strict age limits. If you back up infrequently, retained versions can span a longer calendar period, but the app can only keep versions you've actually created. Backing up once a week leaves no versions for the other six days. Check the dates offered when you restore an important file.
Switching from "1 month" to "1 year" doesn't bring back versions already removed. If you need a particular old version, restore it before changing the preset, since the new pattern may keep a different selection of dates.
When should you use Forever?
Choose "Forever" when you want every saved version and the backup location has room to grow as files change.
Keep an eye on free space and check that each backup completed.
Why is free space not available immediately?
Removing a version from the restore history and reclaiming its disk space are separate steps. Cleanup is attempted on a later normal launch of BackupOnShutdown, with the backup drive connected and no backup running. It doesn't run during backups or when you launch the app through the backup-and-shutdown shortcut. Only data no retained version needs can be freed, so removing a version may reclaim little space.
Do not delete files by hand inside the backup location to make the space appear. Those files can belong to versions you still need. If the drive is tight, use a larger one or add another location, and check that a backup there succeeds before you rely on it.
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