what do you mean to the escrow, if to the account. I really don't know how but I know some how to increase. It will only increase if there is someone want to add trust to you buy donating first. For example, in the signature campaign then you manage it then if the signature campaign is ended the owner would feedback your performances for being a manager to their project. If he like you for being a good manager, you will earn trust by visiting your profile.
To be an escrow you need reputation and trust, trust and reputation cant be build in a short time, one of the way to get reputation is by getting a good review from trusted member whether you get it from managing campaign or doing transaction, and proactive to help other members can become a good way to start gaining reputation