Pick the branch for the session you want
For a casual return run, the default branch is the simpler starting point. For a planned beta test, use beta and read its published changes first. These are recommendations about reducing setup work, not a claim that the default build is bug-free or that beta is always unstable.
Mods can decide the choice for you. If an author's compatibility note names a particular build, use that information rather than assuming that a newer branch improves compatibility. A co-op group should make one shared choice before anyone starts changing installations. The Workshop guide explains the checks to make around dependencies and profiles.
Early Access does not mean every player is on beta
Steam's default branch is the build delivered without a separate branch selection. Optional branches are other builds made available by the developer. A game can be in Early Access while players use either its default build or an optional public beta.
That distinction matters when you read advice. A guide marked beta may discuss a reworked card that behaves differently on your installed build. Check the guide's date and version note, then compare the actual card in your client. Use the patch hub to find the relevant explanation rather than combining the strongest parts of two incompatible builds.
What Steam changes when you switch
In Steam, open the game's Library properties and find Game Versions & Betas. Select only a branch the developer makes available to you, then allow its download to finish. Steam's documentation says branch selection replaces the installed build. Relaunch before checking which version you are running.
Treat save compatibility as a separate question. The ability to select a branch does not tell you whether a run created elsewhere will load correctly. Before changing anything, record your current branch, build, and enabled mods. Finish a run you care about when practical; otherwise preserve an untouched backup using the appropriate save guidance for your setup. Do not overwrite that backup while experimenting.
Use a new test run before committing
After switching, start with a disposable new run. Check the specific behavior you wanted from that branch before moving your regular play there. If you switched to investigate a card change, inspect that card. If the purpose was co-op, test joining with the intended group. A successful launch alone answers neither question.
Keep a short record of the result: branch, displayed version, mod list, and the behavior you checked. This avoids repeating the same test the next time a friend asks which setup worked. If something fails, return to the last known working arrangement only after checking whether any progress now depends on the changed build. Avoid repeated back-and-forth switches on your only save.
Do not switch for an unannounced feature
The September development update describes internal testing without a specific next-patch timeline. Internal testing is not access through the public beta menu. A screenshot, silhouette, or predicted patch number is not a reason to move an important run.
For release-date questions, use the roadmap page. For an evening of actual play, choose a published build your group and mods can use. If you are returning after a break, the returning-player checklist helps narrow the preparation to what your next run needs.